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SCHOOL 



CHEMISTRY. 



CHARLES BASKERVILLE, Ph. D 



, -*. ^. .^ ., 



The University of North Caecltna. 



RICHMOND, VA. 

B. F. Johnson Publishing Co. 

1899. 

A 



39547 

Copyrighted by Charles Baskerville. 
1899. 






WDCOhfca 



( 



JUL 2 ^ 1899 






PREFACE. 



This small book is the outcome of five years' experience in 
teaching teachers in the Summer School of the University of 
North Carolina. The material, which is not new to chemists, has 
been adapted to the needs of the schools in the Southern States, 
with which the author is most familiar. Science now plays an 
important part in the child's education. A large portion of the 
ninety per cent, of high school graduates, who do not secure a 
college or university training, never learn a chemical principle or 
fact except by accident. The course presented is not intended to 
replace college work, but seeks that class of people mentioned, 
who not only wish, but need, to know more of Nature's economy. 
By reference to the cost of apparatus (p. 152)— a serious stumbling 
block hitherto to the introduction of the subject into the curricula 
of high schools, when any one of the excellent elementary treatises 
were used— it will be seen that the laboratory equipment neces- 
sary is reduced to the minimum of cost. By a perusal of the 
experiments given, it will be seen that much store is laid by 
home-made apparatus. 

While a preliminary course in Elementary Physics is desirable, 
such is not deemed necessary to the successful use of this book. 
Some good text-book on Physics, as Gage's, should always be on 
the teacher's table for reference. Richter's " Inorganic Chemistry " 
and Venable and Howe's "Inorganic Chemistry according to the 
Periodic Law," may be profitably used for reference, if the pupil 
desires fuller information on any point. Many words are pur- 
posely introduced into the text to broaden the vocabulary of the 
pupil. Hence a good dictionary should be close at hand. 

For heating purposes, alcohol lamps may be used where gas is 
not handy. 

The course laid out is planned to cover forty weeks, when one 
hour per week is devoted to it. Thirty-seven lessons are given ; the 



IV PREFACE. 

next two periods should be used for blackboard review, using the 
Table of Contents as a guide ; the fortieth period is to be used for 
examination. Experience has taught that the hour may be most 
profitably spent by the following apportionment of time: — Fifteen 
minutes to questioning on last lesson and comments by teacher 
on experiments already performed, attention being called to incor- 
rect conclusions drawn ; fifteen minutes to the reading aloud by 
the pupils of the lesson of the day ; thirty minutes to the per- 
formance of experiments. 

Absolute cleanliness of the laboratory tables and neat note 
books should be insisted upon. Bunsen said one should keep his 
laboratory so neat that he might work there in evening clothes 
without the least fear of soiling them. A good plan is to spread a 
sheet of white paper under all material with which one is working. 
The observations made from the experiments should be accurately 
described by the pupil in note books, clearness of diction being 
emphasized. The results of the experiments in Lesson I are given 
to be used by pupils as a type. 

A diligent and interested teacher, with the aid of succeeding 
classes, can make a valuable collection of many of the substances 
studied. Where possible, the teacher could opportunely omit the 
experiments and take the class on an excursion through concerns 
dependent upon chemical principles — gas and dye houses, fertili- 
zer works, for examples. (See Lesson XXVII.) 

In Lesson XXXV, it is suggested that the teacher read to the 
class from Prof. King's " The Soil " (Macmillan & Co.), pp. 76-106, 
instead of laboratory work. Read slowly, and have pupils write 
what they remember. 

To Dr. F. P. Venable, Professor of Chemistry, and Professor 
M. C. S. Noble, Professor of Pedagogy in the University of North 
Carolina, and Dr. W. L. Dudley, Professor of Chemistry in Van- 
derbilt University, thanks are due for reading the manuscript and 
making many suggestions of value. Mr. E. W. Myers, Engineer 
to the N. C. Geological Survey, kindly made the drawings from 
which the illustrations were made. 

University of North Carolina. C. B. 



Table of Contents. 



To be Used for Blackboard Review. 



LESSON I.— Water.— Importance. Physical States. Solid. 
Liquid. Gas. Matter. Divisibility of Matter. Mole- 
cules. Conservation of Matter. Omnipresence of 
Water 0-13 

LESSON II.— Water (Continued).— Molecular Vibrations. 
Cohesion. Melting Point. Evaporation. Boiling 
Point. Solution, Simple and Chemical. Absorption. 
Mixing. Mineral Waters. Distillation 13-16 

LESSON III. —Atoms.— Atomic Theory. Elements. Com- 
pounds Water Chemically Considered. Hydrogen. 
Occurrence, Preparation and Properties. Chemical 
Affinity 17-21 

LESSON IV. — Oxygen. — Discovery. Occurrence. Prepa- 
ration. Properties. Law of Definite Proportions. 
Allotropism. Ozone. Occurrence and Preparation. 
Medicinal Value 21-26 

LESSON V.— The Atmosphere. — Physically Considered. 
Necessity For. A Mixture. Nitrogen. Value. Dust. 
Carbondioxide. Ammonia. Watery Vapor in Air. 
Dew 26-31 

LESSON VI.— Oxidation. — Combustion. Rust. Flame. 
Incandescence. Heat Aids Oxidation. Oxidation 
Produces Heat 31-35 

LESSON VII. — Nitrogen. —Occurrence. Use. Ammonia. 

Derivation of Name. Preparation. Properties. Uses. 35-38 

LESSON VIII.— Chlorine.— P r o p e r t i e s . Chlorides. 

Bleaching. Nascent State 38-41 



VI SCHOOL CHEMISTRY. 

LESSON IX.— Hydrochloric Acid. — Preparation. Prop- 
erties. Chemical Solution. General Properties of 
Acids 41-43 

LESSON X.— Oxides of Nitrogen. — Laughing Gas. Nitric 

Acid. Preparation. Properties 43-46 

LESSON XL— Carbon.— Allotropism. Diamond. Graph- 
ite. Plumbago. Artificial Diamonds. Jewels. Amor- 
phous Varieties. Charcoal. Coke. Lamp-black. 
Bone-black. Coal : Anthracite. Bituminous. Can- 
nel. Peat 46-49 

LESSON XII.— Elements.— Atomic Weights. Symbols. 
List of Elements, with Symbols and Weights. Val- 
ence. Chemical Equations 49-55 

LESSON XIIL— Acid and Basic Oxides.— Electrolysis. 
Base. Acid. Compound Radicals. Salts. Analysis. 
Synthesis. Metathesis 56-58 

LESSON XIV.— Oxides of Carbon.— Monoxide. Dioxide. 
Law of Multiple Proportions. Preparation and Prop- 
ertiesof these Compounds 59-62 

LESSON XV. — Sulphur. — Properties. Allotropic Forms. 
Crystalline and Amorphous. Sulphuretted Hydrogen. 
Sulphides. Sulphur Waters. Similarity of Hydro- 
gen Sulphide to Water 63-66 

LESSON XVI.— Sulphur Dioxide.— Sulphurous Acid. 
Bleaching. Sulphur Trioxide. Sulphuric Acid. Prop- 
erties. Economic Value 66-69 

LESSON XVII.— Phosphorus.— Allotropic Forms. Dif- 
ference in their Properties. Oxides of Phosphorus. 
Phosphates. Basicity of Acids. Neutral, Acid, Basic 
and Double Salts 69-73 

LESSON XVIH.— Organic Chemistry.— Same Laws Hold 
for All Divisions of Chemistry. Wohler. Vast Num- 
ber of Organic Compounds. Variety of Properties 
Possessed. Safety Lamp. Luminous. Oxidizing 
and Reducing Flames 73-77 



TABLE OF CONTENTS. Vll 

LESSON XIX.— Marsh Gas or Methane.— Substitution 
Compounds. Chloroform. Properties. Organic Hy- 
droxides or Alcohols. Ethyl Alcohol. Conditions of. 
Fermentation. Value of Alcohol as Food. Beverages. 
Warning against Use of. 77-81 

LESSON XX.— Ethers. - Class. Ethyl Ether. Prepara- 
tion. Properties. Organic Acids. Typical. Kadical 
Acetic Acid. Esters. Fats. Butter. Oleomargarine. 
Saponification. Soaps 82-85 

LESSON XX I. — Carbohydrates.— Great Variety of Sugars, 
Grape, Cane, Beet, Sorghum. Artificial Production of 
Sugar. Milk Sugar. Lactic Acid. Starch. Proper- 
ties. Cellulose. Gun Cotton. Collodion. Celluloid 
Paper. Gums 86-90 

LESSON XXIL— Urea.— Organic Bases. Alkaloids. Tea. 
Coffee. Theine or Caffeine. Tannin. Tanning. Tannic 
Acid. Ink. Essential Oils. Resins. Balsam. Rosin. 
Rubber 91-94 

LESSON XXIII.— Metals.— History. General Proper- 
ties of Metals. Electrolysis. Light Metals. Caustic 
Soda and Potash. Flame. Reactions 94-97 

LESSON XXIV.— Magnesium.— Flash Lights. Alumi- 
num. Source. Manufacture. Properties. Uses. Zinc. 
Galvanized Iron , 97-100 

LESSON XXV.— Mercury.— Properties. Amalgams. Tin. 

Sheet Tin. Lead. Poisonous Action 100-103 

LESSON XXVI.— Copper.— Occurrence. Ores. Silver. 
Uses. Noble Metals. Gold. Measure of Fineness. 
Platinum. Malleability. Ductility. Fusibility 104-107 

LESSON XXVII.— Alloys.— Coins. Brass. Bell Metal. 

Type Metal. Casting. Solder, soft and hard 107-110 

LESSON XXVIII.— Iron.— Occurrence. Ores. Impuri- 
ties. Manufacture. Iron Furnace. Cast Iron (white 
and gray). Cold Short. Hot Short. Steel. Temper- 
ing. Wrought Iron 111-115 



Vlll SCHOOL CHEMISTRY. 

LESSON XXIX.— Metallic Oxides.— Colored Oxides. 
Lime, Quick and Slaked. Paints. Water Colors. Oil 
Paints. White Lead. Zinc White. Adulterants. 
Gems. Welsbach Lights. Calcium Light 115-118 

LESSON XXX.— Chlorides.— Sodium Chloride. Salt 
Beds. Salt Gardens. Salt Springs. Impurities of 
Common Salt. Uses and Value. Silver Chloride 119-122 

LESSON XXXI.— Nitrates.— Sodium and Potassium Ni- 
trates. Nitre Plantations. Purification by Crystalli- 
zation. Gunpowder: History and Composition. 
Products of Explosion. Nitro-glycerine. Dynamite. 
Silver Nitrate 123-126 

LESSON XXXII— Carbonates.— Neutral, Acid and Basic 
Carbonates. Chemical Action Promoted by Solution. 
Leblanc Process. Solvay and Castner Kellner Pro- 
cesses. Potassium and Ammonium Carbonates. Sta- 
lactites and Stalagmites 126-131 

LESSON XXXIII.— Sulphates. -Neutral and Acid Salts. 
Sodium, Magnesium and Calcium Sulphates. Plaster 
of Paris. Copper and Ferrous Sulphates. Tri-Acid 
Bases. Alums. Phosphates. Universal Distribution. 
Mines. Calcium Phosphates. Double Phosphate 131-135 

LESSON XXXIV.— Silicates.— Natural and Artificial. 
Mortar. Cement. Hydraulic Cement. Glass : Bohe- 
mian, Flint and Bottle Glass. Borax 135-138 

LESSON XXXV.— The Soil.— Source. General Simi- 
larity in Composition. Elements Present in the Soil. 
Essential Elements for Plant Growth. Nitrification. 
Bacterial Inhabitants. Source of and Necessity for 
Sun's Heat 139-142 

LESSON XXXVI.— Synthetic Life.— Plant Life. Osmo- 
sis. Tobacco. Abundance of Plant Food in Virgin 
Soil. Necessity for Fertilizers. Poor Land. Kinds 
of Fertilizers. Fixation of Carbon 142-148 

LESSON XXXVII.— Cycle of Life.— Animal Growth. 
Cooking. Necessity of Air. Animal Heat. Animal 
Life. Analytic. Delicate Balance of Our Existence.. 148-151 



School Chemistry. 



LESSON I. 

WATER. 

1. Importance. — Did you ever notice that, when a 
man starts to build a house, one of the first things he 
does is to find the nearest source of water supply? 
Do you know that most of the prosperous towns or 
cities are located upon the banks of some stream, or 
lake, or arm of the sea ? Did you ever observe that 
many of the country houses are near a spring, creek, 
or lake ? Ask one of the aldermen of your place how 
much money the town spends for water. How long 
do you think you could go without drinking any 
water ? 

2. Physical States. — " Oh ! water is such a simple 
thing," you exclaim. If you heat water sufficiently, 
you know it boils ; it turns into steam ; it seems to 
disappear ; it evaporates. If you hold a cold plate 
over the top of a boiling kettle, you notice that the 
hot steam condenses and you get some of the water 
back again. How often you have seen the icicles 
hanging from the roof of the house ! If you place a 
lot of them in a tin cup and put it upon the stove, 



1 SCHOOL CHEMISTRY. 

you see them melt down to water ; and leaving the 
cup there long enough, the water boils and passes off 
as vapor. We thus see the solid changed into a liquid, 
and then into a gas. These are the three physical 
states of matter — solid, liquid and gaseous. Almost 
all substances can exist in these three interchangeable 
states. 

3. Matter. — But what is matter ? Anything that 
^occupies space and has weight is matter. Steam or 

any other gas has weight ; so has a cannon ball or a 
potato; and as each " takes up room," it is a form of 
matter. 

4. Divisibility of Matter. Molecules. — If with 
a sharp knife we cut a potato in half; then halve one 
of these two parts ; in turn halve one of the quarters ; 
then split one of the eighths, eventually the piece will 
be so small that you cannot hold it in order to cut it 
further. Shall we therefore assume that it is impos- 
sible to further subdivide this small particle because 
we have not the proper instruments to work with? 
No ; but let us imagine ourselves with the very finest 
tools. We could continue tfre subdivision until the 
particle became very, very small. The ancient Greek 
philosophers were divided into two great schools of 
thought. One school maintained that the division 
could continue until nothing remained ; i. e., that 
matter is infinitely divisible. The other claimed that 
a point would be reached beyond which no subdivision 
would be possible ; because, following the former rea- 



WATER. 11 

soning, matter would be composed of an infinite 
amount of nothing. The generally accepted theory 
to-day is that matter is composed of very minute par- 
ticles, which by themselves are not appreciable to the 
senses, yet maintain the properties or characteristics of 
the substance. These small particles are called mole- 
cules. At a distance we see only a pile of bricks ; we 
do not see the individual bricks. A molecule corres- 
ponds to a single brick in the pile. It is the smallest 
particle of matter which retains its properties, a part 
of the whole, and, if broken up, it ceases to be a brick, 
or molecule. 

5. Conservation of Matter. — When you heated 
the water you did not destroy it. You allow it to 
freeze by standing out in the cold over night ; you 
obtain the liquid again when the ice thaws. We 
might say, therefore, that it must be a substance that 
we cannot break up by heat or cold ; i. e., elementary, 
although we can get it into very fine particles. Snow- 
flakes are only tiny frozen particles of water. They 
are so small, too, that they can sift in, down or up, 
through very small cracks. We can neither taste nor 
feel the tiniest snowflake, yet one of them changes 
easily into liquid water. These little crystals seem to 
be molecules of water. They are not, however. Mole- 
cules are even smaller, and the beautiful snow crystals 
are aggregations of numbers of molecules. 

6. Omnipresence of Water. — Water is present in 
almost all substances we know. It is in the air, as 



12 SCHOOL CHEMISTRY. 

evidenced by the rains and dew. It is in many rocks, 
although we do not see it, and in the soil. Plants and 
animals are largely composed of water, with a small 
proportion of mineral matter. It is omnipresent, and 
a most difficult problem with a chemist is to get a sub- 
stance dry — absolutely free from water. 

EXPERIMENTS. 

I. Allow some ice to melt in a tin cup ; note the temperature of 
the ice with a thermometer, and also the water produced by the 
melting of the ice. Heat the cup until the water boils, and note 
the temperature of the boiling water and the steam. Hold a dry 
plate over the boiling water, and incline it so that the condensed 
steam may be caught in another cup. (Can you make the water 
get hotter by more vigorous and longer heating?) 

II. In a small glass tube, closed at one end, heat a little soil that 
appears dry ; in another, heat a crystal of laundry soda or alum ; 
in a third tube, heat gently some green twigs. 

III. Cleanse two empty tin cans. Make a hole in the bottom of 
each with a nail. Fill one of them with clean sand ; the other 
with any kind of soil. Place them upon glasses and pour in a 
dipper of water, and let stand until the next lesson. 

A typical page from a note book : 

(Date.) 

1. The temperature of ice is zero ; that of boiling water 100°. I 
observe that the solid ice changes to liquid on applying heat, and 
that the temperature of this liquid remains near zero till all the 
ice is melted. If the heating be continued, the liquid changes to 
a gas. When the heated vapor comes into contact with the cold 
surface of the plate, I observe that water is obtained. I would 
conclude that the three physical states depend upon the addition 
or subtraction of heat ; in the former case, the changes are from 
the solid to the liquid, and then to the gaseous state ; in the latter, 
the converse is true. 



WATER. 13 

2. In all three of these experiments, I proved the presence of 
water in substances that appeared dry. As the materials used are 
very diverse in character, water must be widespread in its occur- 
rence. 

3. I observe that water passed through the two cans packed re- 
spectively with sand and dirt. That which passed through the 
sand was crystal in appearance ; that which came through the soil 
acquired color and odor different from the original water. I con 
elude that if water passes through this small amount of soil, much 
of our rains must penetrate the earth ; and, when the water makes 
its appearance again in springs or wells, it may have acquired an 
odor and color. This must depend upon the kind of soil through 
which it has passed. 

(Name). 



LESSON II, 

WATER (Continued). 



7. Molecular Vibrations. — From an experiment 
in our last lesson we learned that ice melts at zero, 
and water boils at 100° C. There is a natural law by 
which, when a substance is heated it expands. This 
is explained by supposing the molecules to be in con- 
tinual vibratory motion. Heat augments this vibra- 
tory motion of the molecules, and increases the range 
of these movements ; expansion is the result. 

8. Cohesion versus Vibratory Motion. — Solids 
hold their shape through the influence of a powerful 
force called cohesion, which binds the molecules to- 
gether. The vibratory motion of the molecules tends to 



14 SCHOOL CHEMISTRY. 

overcome this cohesion. In solids the latter is stronger, 
but in liquids, that binding force is largely overcome, 
and the molecules have greater freedom of motion. 
In water, for instance, -the molecules move so easily 
over one another that the shape of the liquid depends 
upon the confining walls of the containing vessel. If 
the vibration of the molecules be even' greater, the en- 
tire cohesive force may be eventually overcome. Such 
is the case in gases, where instead of attraction, there 
seems to be an actual repellent force acting between 
the molecules. 

9. Melting and Boiling Points. — These molecu- 
lar vibrations in a solid are increased by heat until a 
point is reached when the substance fuses or assumes 
the liquid state. This is called the melting point. 
On further addition of heat to the liquid, the move- 
ments of the molecules become more and more active, 
resulting in greater expansion. A time comes in the 
heating when the molecules rush off into space with 
some violence ; the liquid boils. The temperature at 
which this takes place is called the boiling point. 
Many molecules of a liquid in their restless vibration 
pass off below the boilng point, presenting to us the 
phenomenon of evaporation. For this reason, bottles 
of perfume have to be kept stoppered when not in 
use. 

10. Solution. — If we place a substance in a liquid 
and the substance disappears — that is, unites with the 
liquid to form a homogeneous fluid — it is said to dis- 



WATER. 15 

solve, and a solution results. We all know that water 
will dissolve sugar and salt. It dissolves many sub- 
stances, but there are many substances it does not 
dissolve. A gas, when dissolved, is commonly spoken 
of as being "absorbed." When one liquid dissolves 
another, they are said to be "mixed." 

11. Solvent Action of Water. — There is much 
material existing in the soil that is soluble in water- 
If you pour water upon a pile of sand, you see the 
water disappear ; it sinks out of sight. Sand, one of 
the chief ingredients of the soil, gives it porosity, per- 
mitting it to drink up large quantities of water. This 
water, breaking up into small particles, easily passes 
through the little spaces between the soil grains, dis- 
solving something here, something there, as it goes. 
No water which comes from the earth, therefore, is 
perfectly pure, however bright it may appear or pleas- 
ant it may be to the taste. The presence of many 
impurities is frequently easily detected in the waters of 
many rivers and springs by an unusual color or the 
possession of some peculiar odor or taste. When 
mineral constituents are present in rather more than 
usual amounts, it is said to be a mineral water, as 
chalybeate (iron), sulphur, or lithia. If calcium (dis- 
solved lime) is present in notable amounts, the w r ater 
is said to be hard. 

12. Distillation. — Gases are more soluble in cold 
water than hot, so we may get rid of them by boiling. 
The mineral substances that may be dissolved do not 



16 



SCHOOL CHEMISTRY. 



volatilize on heating as readily as does water, so we 
may purify water by changing it into steam and then 
condensing it (by cooling) to the liquid form again. 
The first portion of the condensed water is liable to 
contain the gases, and should be rejected. Life does 
not. continue at the temperature of boiling water ; 
hence by this means all living organisms, called bac- 
teria, the source of many diseases, are destroyed. Water 
may be best purified, therefore, by distillation. 

EXPERIMENTS. 

I. (a) Set up apparatus, as shown in Fig. 1, and distil th« water 
collected from the last experiment, (b) Dissolve some salt in 
water; taste, distil; taste distillate (condensed steam), (c) Place a 
few drops of red ink in some water and distil, (d) Add a drop of 
ammonia to some water and distil, collecting in four separate por- 
tions; smell each one. Save some of the pure water obtained 
from a, b and c. 




Fig. 1 



■Distillation flask. B— Condenser. C— Receiver. D— Tank 
containing water, which keeps the condenser cool. 



ATOMIC THEORY — HYDROGEN. 17 



LESSON III. 

ATOMIC THEORY. HYDROGEN. 

13. Water a Compound. — Having obtained some 
pure water, and not being able to decompose it by heat 
or cold, let us see if we can produce in it any other 
than a physical change. If we drop a piece of the 
metal potassium upon some of our purified water, we 
observe light and heat. A gas, which we shall learn 
later does not come from the metal, escapes and takes 
fire. Some great change has evidently taken place in 
the water. We have decomposed it. Water is a com- 
pound, not an element, although it was thought to be 
so by the Greeks long years ago, and even by people 
everywhere till near the close of the last century. 

14. Atoms. — The minutest amount of water that 
would still be water would be a molecule. But water 
may be decomposed, as we have just seen, into some- 
thing which is no longer water ; consequently we know 
that the molecule can be further subdivided. The 
very small particles of which the molecule is composed 
are called atoms, and, in the case of water, they no 
longer resemble that liquid at all. An atom is the 
smallest possible particle of substance we know of; 
that is, it matters not how it may be treated, cooled, 
heated, or what not ; it may be caused to combine 
with some other substance, but no one can now know- 
ingly change or destroy it. It may be done some day. 



18 SCHOOL CHEMISTRY. 

The old alchemists, living centuries ago, believed that 
one element could be changed into another, and tried 
to make gold by heating mercury and sulphur together. 

15. Elements and Compounds. — If the atoms com- 
posing a molecule are alike, the molecule is elemen- 
tary. If the atoms are unlike, we have a compound 
molecule. A water molecule is made up of atoms of 
two different gaseous elements, as we shall learn, hence 
it is a compound, and not an element, as was once 
thought. 

16. Atomic Theory. — To review : the smallest in- 
divisible particle is an atom ; atoms combine in mole- 
cules ; if alike, an elementary ; if unlike, a compound 
molecule ; a number of molecules constitute mass — 
that is, any appreciable amount of matter. As matter 
has weight, those particles of which it is composed 
must also have weight ; hence the atoms have weight. 
The atoms of the different elements have their own 
constant fixed weights, called atomic weights, which, 
as far as we now know, is unalterable. Such in sub- 
stance is the Atomic Theory as propounded by John 
Dalton in 1803. 

17. Hydrogen. — The gas given off when potassium 
or sodium acts upon water is the lightest substance 
known to chemists ; the weight of its atom is therefore 
taken as the standard of atomic weights and placed at 
unity. This gas is called hydrogen. Set it afire and 
it burns with a pale blue, very hot flame, A mixture 



ATOMIC THEORY — HYDROGEN. 19 

of hydrogen with air is very explosive, hence the 
greatest care should be exercised when experimenting 
with this gas. 

18. Occurrence. — This light substance is found free 
on the earth only in the gases of some volcanoes and 
certain natural gas wells. It is said to occur abun- 
dantly, however, in the atmosphere of the sun and of 
many fixed stars. On earth, hydrogen occurs com- 
bined in all animal and vegetable matter, and consti- 
tutes one-ninth of water (by weight). 

19. Preparation. — Hydrogen can best be prepared 
on the small scale by treating scraps of zinc with 
dilute hydrochloric or sulphuric acid. As the metallic 
zinc is dissolved, the gas is evolved. It is collected 
over water, but, as it is so light, it may also be caught 
by holding an inverted bottle over the exit tube (up- 
ward displacement of the air). 

20. Chemical Solution. — In our last lesson we 
learned that when sugar or salt was dissolved in water 
a simple solution resulted. The sugar or salt may 
be easily recovered by boiling away the water. No 
real change has taken place in the sugar or salt. 
Should we evaporate the water from some of the solu- 
tion obtained by dissolving the zinc in the acid, we 
should not recover the zinc as metal, but instead a 
white crystalline substance possessing very different 
properties. Quite a complicated process is necessary, 
in fact, to change this white substance back into the 



20 SCHOOL CHEMISTRY. 

gray metal. This is a solution just as much as the 
other, only the action is not mainly physical but 
chemical, brought about by one of those powerful 
forces of nature called chemical affinity. Chemistry 
is that branch of science which treats not only of the 
different kinds of matter, but as well of the changes 
brought about by means of the force mentioned. 



EXPERIMENTS. 

I. Test a little of the pure water obtained in last experiment 
with red litmus. Drop a piece of the metal potassium on the 
water. When the violent action has ceased, test again with the 
litmus paper. 

II. Immerse a test tube mouth upwards in a pan of water* ; as 
soon as all the air has escaped, invert the tube, which will now be 
filled with water. Grasp a piece of sodium half as large as a pea 
with a pair of dry tweezers, and quickly thrust it into the water 
and under the mouth of the test tube. When filled with the es- 
caping gas, place the thumb over the mouth of the tube, and 
while it is still inverted bring close to the flame removing the 
thumb. 

Caution. — Never handle sodium with wet hands or tools. 

III. Fit up apparatus like that shown in Fig. 2. Add 10 cc. f 
dilute hydrochloric acid to several small pieces of zinc in the bot- 
tle, (a) Collect several tubes full of the gas over the pneumatic 
trough, throwing away the first three. Why ? Collect one tube full 
by upward displacement. Test all by holding to a flame, (b) At- 
tach the exit tube to a clay pipe by means of a rubber tube, and 
fill some soap bubbles with the gas. Prepare soap suds by using 



*A vessel filled with water and used in working with gases as above, is 
called a pneumatic trough, an invention of Priestly. 

tCc.=cubic centimeter ; cm.=centimeter. 



OXYGEN — OZONE. 



21 



Castile soap and adding a little glycerine, (c) Substitute for the 
clay pipe a straight hard glass tube about 6 cm. long, drawn out to 
a small bore. After a minute, set fire to the gas coming out. Hold 
a dky tumbler down close over the flame. 

IV. Take some of the solution formed by the action of the acid 
upon the zinc in the above, and boil away most of the liquid. 
Cool. Do vou obtain metallic zinc ? 




Fig. 2. 



LESSON IV. 



OXYGEN. OZONE. 

21. Oxygen. — Having found that one of the con- 
stituents of water is a gas, let us see of what else it is 
composed. In the latter part of the third experiment 
in our last lesson we observed that water resulted when 
hydrogen was burned in the air. As we shall soon 
learn, the air is mainly a mixture of two gases. In 
one of these, hydrogen does not burn at all ; but in 
the other it does burn, giving out great heat and pro- 
ducing water as the result of its burning. This latter 
gas is oxygen, which in the free state constitutes one- 



22 SCHOOL CHEMISTRY. 

fifth by volume of our entire atmosphere. It is very 
abundant, occurring not only free, but combined with 
almost all known elements. About two-thirds of the 
earth is composed of this gaseous element. 

22. Discovery. — It is generally accepted that 
Priestley, an English preacher, discovered oxygen in 
1774, by heating the red oxide of mercury with a sun 
glass. Lavoisier, a French savant, named it oxygeD 
meaning " acid producer." 

23. Preparation. — We may prepare the gas as did 
Priestley in his original experiment, or best by heating 
a mixture of potassium chlorate and black oxide of 
manganese (manganese dioxide). The gas is collected 
over water. 

24. Properties. — Oxygen is a colorless, odorless 
gas, and what is known as a supporter of combustion. 
A fire burns in the air on account of the oxygen that 
is present. If the flame of a lighted match be blown 
out and only the glowing stick be thrust into a tube of 
oxygen, it will burst out again with flame. The less 
oxygen there is present, the less brilliantly does the 
taper burn. The more oxygen there is present, the 
more vigorous is the fire ; hence oxygen is a supporter 
of combustion. What is true of the flame is also true 
of the human body. We breathe solely that we may 
bring oxygen into our lungs to carry on there and 
throughout the body a similar process, viz : combus- 
tion, but one of very much less violence. 



OXYGEN — OZONE. 23 

25. Law of Definite Proportions.— By passing an 
electric current through acidified water we decompose 
it. At the negative pole of the battery we will 
observe twice as much gas liberated as at the positive 
pole. If we test these gases with lighted tapers, we 
find one to be hydrogen and the other oxygen, liberated 
in the proportion of two volumes to one, respectively. 
We have seen that by burning hydrogen in the air we 
obtain water ; we can decompose water into two gases ; 
hence we learn the composition of water by synthetic 
and analytic means. Further, hydrogen and oxygen 
are always present in water in the proportion of two 
volumes to one. If that ratio be altered in the least, 
that gas which is present in greater amount than 
necessary for the ratio of two to one (by volume) will 
be left over when the hydrogen and oxygen are caused 
to unite to form water. In short, in no other propor- 
tion will these two gases unite to produce water. This 
is true of all chemical compounds, namely, that the 
same elements always enter into the same compounds in 
the same proportion. If the proportion varies, the 
compound produced is different. 

26. Allotropism. — Ordinarily an elementary mole- 
cule is composed of two atoms. Such is the case with 
hydrogen and oxygen. It is possible to imagine three 
or even more atoms in the molecule. We have an 
example of this in oxygen. The ordinary molecule 
contains only two atoms, while ozone contains three ; 
that is, a molecule of this latter substance weighs half 
as much again as one of oxygen. When an element 



24 SCHOOL CHEMISTRY. 

exists in two or more different forms, it is termed allo- 
tropism. In one hand you may hold two eggs, com- 
parable to the oxygen molecule ; in the other, three 
eggs, which may be compared to the ozone molecule — • 
an egg representing an oxygen atom. 

27. Ozone. — The peculiar odor noticed around some 
large electric dynamos when they are running is due 
to ozone. The odor of the oil must not be mistaken 
for that of ozone, which is produced by the discharge 
of electricity in oxygen or the air. It is also produced 
by the slow oxidation of phosphorus in moist air. 
Aside from the peculiar odor by which it may be de- 
tected, we can test for it with paper which has been 
previously moistened with a solution of potassium 
iodide and starch. The ozone decomposes the potas- 
sium iodide, liberating free iodine, which combines 
with the starch to produce a blue colored compound. 

28. Medicinal Value. — Ozone is very much less 
stable, but far more active chemically, than oxygen. 
It is decomposed by decaying organic substances ; 
hence, in and about large cities, where much filth 
accumulates, there is very little ozone in the air. 
Lightning produces the ozone in the air. It is said 
that the waves beating upon the rocks on the seashore 
produce ozone. This allotropic form of oxygen kills 
the germs which cause many diseases, as pulmonary 
troubles. Our doctors send us to the mountains or the 
seashore, where the ozone renders the air crisp and 
exhilarating. Air containing too much ozone is 



OXYGEN — OZONE. 



25 



very irritating, and in a concentrated form ozone is 
poisonous. 

EXPERIMENTS. 

I. Set up apparatus like that shown in Fig. 3. Place half a tea- 
spoonful of red oxide of mercury in the tube A, which should be of 
hard glasa. Heat. Collect the gas evolved over the pneumatic 
trough. Test about the third tube of gas, open end up, by plung- 
ing in a splinter, which, having been lighted and blown out, has a 
spark on the end. 




Fig. 3. 

II. Place a teaspoonful of a mixture of two parts of manganese 
dioxide, and three parts of potassium chlorate in apparatus like 
the above, and heat. After the air has been expelled, collect four 
tubes and one bottle full of the gas. (a) Test one with a lighted 
taper, (b) Hollow out the end of a piece of chalk 3 cm. long. 
Bind this, hollow end up, to an iron wire. Place a piece of phos- 
phorus the size of a pea in the hollow ; set fire to it and plunge 
into the second tube.* (c) Bind a piece of charcoal to a wire with 
smaller wire ; heat one corner of the charcoal until it begins to 
glow, and then plunge it into the third tube, (d) In the fourth 



♦CAUTION. — Never handle phosphorus with the bare hands, except 
under water. Use tweezers or a pin. Always cut it under water. 



26 SCHOOL CHEMISTRY. 

tube place a piece of moist potassium iodide starch paper. Pre- 
pare the starch paper by boiling several grains of starch in water 
in a test tube until dissolved ; add a crystal of potassium iodide 
and use the liquid to moisten strips of filter paper. These strips 
may be dried in the air and kept in a corked bottle, (e) Bind a 
thin watch spring on an iron wire. Warm the free end of the 
spring, and touch it to a small piece of sulphur. Set fire to the 
sulphur, which should be attached to the spring, and plunge into 
the bottle of oxygen. Repeat experiment if no violent action 
takes place. 

III. Place a piece of phosphorus 2 cm. long in a wide-mouthed 
bottle; add enough water to almost submerge the phosphorus; 
cover the bottle with a piece of glass, and allow to stand twenty 
minutes. Note the odor of the air in the bottle, and drop in a 
piece of wet potassium iodide starch paper. 



LESSON V. 
THE AIR. 



29. The Atmosphere. — Lying prostrate upon the 
ground on the edge of some lake or stream, have you 
not often watched uhe fish gliding hither and thither 
in the water? Did you ever realize that we, too, live 
in a great ocean ? We do, but our ocean, as we come 
in contact with it, is not liquid, but gaseous, and com- 
pletely envelopes the earth. The whirlwinds and tor- 
nadoes are the whirlpools and currents of the ocean in 
which we live. 

30. Thickness and Necessity of Air. — You do 

not see some gases, but imagine yourself standing afar 
off somewhere looking at the world with the power of 



THE AIR. 27 

seeing air. The atmosphere would appear to you as 
liquid water appears to you now. You would see the 
birds floating around in it, but not reaching the surface, 
for the highest flying bird, the condor, never soars 
more than five miles from the earth, and this aerial 
ocean of ours is at least one hundred miles deep. We 
people, who live and move around on the earth, would 
be to you "deep air" creatures, like some of those 
strange, weird looking animals which live along the sea 
bottoms. Suppose you fished for us and caught one of 
us so foolish as to bite your bait and jerked him from his 
ocean home. You would see him gasp and die just as 
the many little sunperch you have so frequently drawn 
with such delight from the pool. The air is not neces- 
sarily always a gas, for by complicated apparatus it 
may be liquefied and then frozen to a solid, as we know 
is possible for water. 

For a long time the ancients regarded air as an ele- 
ment, as they did water. We found water, however, 
to be a compound and not an element ; possibly we 
may make the same discovery with regard to air. 

31. Air a Mixture. — Phosphorus, as we have 
learned, combines with oxygen, producing flame. If 
we set fire to a piece of phosphorus enclosed in a defi- 
nite volume of air confined over water, at first we note 
a very violent action taking place. Dense white fumes 
are produced, and after the phosphorus ceases to burn, 
the white fumes, phosphorus oxides, are gradually ab- 
sorbed by the water which rises up into the jar. When 



28 SCHOOL CHEMISTRY. 

all the fumes have disappeared, and the jar is quite 
cold again, we will notice, if we lower the jar into the 
water until the water stands at the same level on both 
sides (inside and out), that one-fifth of the air has been 
burned up by the phosphorus. The portion which has 
been used up is oxygen, which makes up one-fifth by 
volume of the atmosphere. Should we test the remain- 
ing gas in the bottle with a lighted taper, we would 
see the fire extinguished, thereby proving that its na- 
ture is very different from that of oxygen. It is a very 
inert gas — called nitrogen. Air is a mixture of these 
two gases. It is not an element, nor is it a compound, 
as no chemical action results when nitrogen and oxy- 
gen are mixed in the proportion of four to one ; and 
the mixture has all the properties of air, as may be 
proven by the experiment just recited. 

32. Oxygen Necessary for Life. — The oxygen is 
that portion of the air we use when we breathe. Should 
we shut up a mouse in a closed jar, as we did the phos- 
phorus, he would soon use up all the oxygen and die 
from suffocation. From this all of us can see how 
foolish it is to live in rooms that are closely shut up or 
to sleep with the head under the bedclothes. 

33. Role of Nitrogen in Air. — Doubtless some of 
you will say : "If oxygen is so necessary for life, 
couldn't we live much better in pure oxygen?" Let 
us reason it out. Oxygen combines with phosphorus 
or carbon producing heat. Our bodies are kept warm 



ffiE AIR. 29 

by the heat resulting from the union of oxygen with 
carbon compounds. We breathe out the inhaled oxy- 
gen as carbon dioxide. If the air were pure oxygen 
our bodies would rise to a fever heat and even higher, 
and all the fires and lights in the world would burn 
furiously. A fire once started would spread all the 
world over, and only an Almighty Power could check 
it. Therefore, this lazy, inert gas, nitrogen, has great 
value, as it serves to dilute the oxygen, thus retarding 
its rate of combining with other substances. 

34. Other Constituents. — We know that the air 
contains many impurities dependent entirely upon the 
locality. Some of these impurities evidence themselves 
by disagreeable odors noticed about glue, fertilizer, or 
perfume factories ; emanations from new-made ground, 
stables, and so forth, Suspended dust is almost a con- 
stant impurity in the air. Its presence is shown by 
allowing a beam of sunlight to enter a dark room. 
But there are two other gases always present in the air, 
though in small amounts. Inhaled oxygen is con- 
verted into carbon dioxide and exhaled as such. In 
ten thousand parts of air there are about four parts of 
this carbon dioxide — a small quantity, }^et of great 
value, as we shall see. You scarcely imagine " spirits 
of hartshorn " existing in the air. It is always present, 
however, but in exceedingly small amounts, a few parts 
in the million. These two gases in the air are essen- 
tial to plant and animal life, but no more so than the 
vapor of water, which is always in the air. 



30 SCHOOL CHEMISTRY. 

35. Water Vapour in Air. — Warm or hot air will 
absorb very much more water vapour than will cold 
air, hence when warm air, which has been saturated 
with water, is chilled, we have rain, or snow, or hail. 
This occurs on a small scale when " dew falls" at 
night. It does not fall at all. The air during the 
daytime becomes warm by the action of the sun's rays, 
and then absorbs more water vapour. The grass 
and objects of similar nature cool more rapidly at 
night than does the air, so the moisture of the air is 
merely condensed on these colder surfaces. If we 
bring a pitcher of very cool water into a warm room, 
we see the moisture of the air condense on the sides of 
the pitcher. Air that is devoid of moisture is very 
trying, because it dries up the body, absorbing the 
Water from the animal fluids to supply its own thirst. 
Fortunately, the body can in time adjust itself to new 
conditions, and the lack of water can be supplied by 
drink. 

EXPERIMENTS. 

I. Fill a small, tall bottle with water and place it in the pneu- 
matic trough so that it will project about a centimeter above the 
surface of the water. On the bottle place a shallow piece of por- 
celain, holding a piece of phosphorus about the size of a pea. Ig- 
nite the phosphorus with a hot wire and quickly cover with a 
wide mouth bottle ; empty quinine bottle will do. Hold the bot- 
tle firmly until the phosphorus has ceased burning. Allow the 
bottle to stand in the water until perfectly cold, and the dense 
white fumes of phosphoric oxide have been absorbed. Raise or 
lower the bottle until the water which has risen on the inside is 
on a level with that on the outside. Why do this ? Measure with 
a rule the height of the bottle above the surface of the water and 
the entire length of the bottle. State your conclusions. 



OXIDATION. 81 

II. Expose some clear lime water in an open glass vessel to the 
air for half an hour. What do you see? Lime water, which is 
prepared by slacking quick lime and filtering, becomes milky, 
with carbon dioxide, owing to the formation of a white solid. 

III. Blow a deep breath into a solution of clear lime water in 
a test tube by means of a small tube. 

IV. Test some of the gas left in the bottle in the first experi- 
ment. Does it act like oxygen or hydrogen ? 



LESSON VI. 
OXIDATION. 



36. Oxidation. Combustion. — We have seen that 
phosphorus and charcoal burn more brilliantly in 
oxygen than in air. We also saw that if no oxygen 
be present the fire is extinguished, whereas even a steel 
watch spring will burn in oxygen. The burning of a 
substance is called combustion. The substance burned 
is said to be combustible, and the substance, usually a 
gas, which promotes the burning or makes it possible, 
is called a supporter of combustion. When the sup- 
porter of combustion is oxygen, as in the cases men- 
tioned, the process is termed oxidation. 

37. Rust. Flame. — We all know that bright 
metallic surfaces will rust on exposure to moist air. 
If the air be perfectly dry, no rusting takes place ; the 
presence of water therefore seems necessary. There 
are other substances which will cause the rusting to be 



32 SCHOOL CHEMISTRY. 

more rapid, but they frequently serve merely to hold 
a thin film of moisture on the metal. This rust is 
nothing more than a compound of the metal with 
oxygen. Its color is red-brown with iron, black with 
copper, and is the result of oxidation. It is exactly 
similar to the burning of the steel spring in oxygen, 
only in the latter case it is more rapid. When oxida- 
tion is very rapid, we call it combustion. Flame is 
usually one of the results of combustion. The lumi- 
nosity of the flame is due to the glowing of particles 
of the burning substance so intensely heated. We 
may have both light and heat without flame. 

38. Incandescence. — Suppose we have three wires, 
one of lead, one of platinum, and one of magnesium, 
and heat each of them in a flame. When we set fire 
to a substance, we say we "ignite it." Sometimes it 
will melt or fuse, as in the case of the lead wire. 
Again it will not, but becomes red, then white hot, 
without melting or oxidizing. The platinum wire 
thus, we say, becomes incandescent, it glows. No 
change, except a physical one, takes place in either of 
the cases mentioned, except the small amount of oxida- 
tion which the lead may undergo, and that is insignifi- 
cant. Now, when we try the magnesium wire, we see 
that' it burns with a brilliant light. The white 
powdery substance left is entirely different from the 
gray metallic wire we used. A chemical change has 
taken place. The white powder is the oxide of 
magnesium. 



OXIDATION. S3 

39. Oxidation Aided by Heat. — If we expose a 
piece of magnesium wire to moist air or oxygen for a 
long time, we should see that the white powder would 
be produced finally, but no flame would result. To 
make the oxidation rapid, then, we see that heat must 
be added to facilitate the union of the substance (metal 
in this case) with the oxygen. A mixture of one 
volume of oxygen and two volumes of hydrogen — that 
is, in the proportion to produce water — is harmless 
until a lighted match, or other source of heat, is 
brought in contact with it. The oxidation is then so 
rapid that a violent explosion results. Such experi- 
ments are too dangerous for any one not acquainted 
with all the conditions to perform, so we shall have to 
omit an ocular demonstration of this important prin- 
ciple. 

40. Heat, a Result of Oxidation. — It is a law of 

chemical force that, when one element unites with 
another, heat is produced. When the iron or magne- 
sium wire slowly rusts — becomes oxidized in the air — 
the same amount of heat is produced as when the 
rapid combustion takes place, only it is spread out 
through such a long time that the heat is dissipated or 
seemingly lost. We have substances, however, which 
of their own accord become oxidized in the air — slowly 
at first, then rapidly, and finally burst into flame. 
Such substances are said to be spontaneously com- 
bustible ; that is, by gradual oxidation the heat gen- 
erated accumulates to such an extent that the tem- 
perature of the body is raised to the ignition point, 



u 



SCHOOL CHEMISTRY. 



at which oxygen rapidly combines with it. Many 
fires, especially in mills and factories, result from just 
such a cause. Old rags, usually greasy, and refuse 
matter are piled away. Oxygen combines with some 
of the oily substances, producing heat, which gradually 
accumulates in sufficient quantity to raise some of the 
material to the temperature of ignition, and fire is the 
result. 

Therefore, to have fire, we require a combustible 
substance, a supporter of combustion, and sufficient 
heat to raise the temperature of the material to the 
point of ignition. 

EXPERIMENTS. 

I. Place a small pinch of red lead (oxide of lead), mixed with 
powdered charcoal, upon a piece of charcoal, and heat it with a 
blowpipe, directing the flame obliquely upon it (Fig. 4). Oxygen 
combines very readily with the charcoal, leaving the metal behind. 
Copper oxide may be substituted for the red lead, but longer heat- 
ing is necessary. 




Fig. 4. 



NITROGEN— AMMONIA. 35 

II. Carry out the experiment with the three wires, as given in 
the lesson to day. 

III. Expose a piece of dried phosphorus upon a dry plate in a 
jar of oxygen. Dry the phosphorus by pressing in a dry towel or 
piece of paper. Do not rub it ! ! 



LESSON VII. 
NITROGEN. AMMONIA. 

41. Nitrogen. — After removing the oxygen from 
the air by burning it out with phosphorus, we found 
the remaining gas to be a very lazy substance. It is 
quite different from either hydrogen or oxygen, being 
neither combustible nor a supporter of combustion. 
Free nitrogen is, in fact, a very inert, inactive substance, 
possessing neither taste nor odor. Freshly boiled 
water can absorb one and a half per cent, of the gas 
however. 

42. Occurrence. — Free nitrogen gas constitutes 
four-fifths by volume, as we have seen, or three-fourths 
by weight, of the atmosphere. Combined with hydro- 
gen, it is present in small quantities in the air. It 
is present in nitrates, commonly as " saltpetre," or 
" nitre," from which its name is derived. Nitrogen 
combines directly with very few elements. Indirectly 
nitrogen may be made to combine with many of the 
elements, producing bodies varied in character, and 
frequently, powerfully reactive. Nitrogen is also 



36 SCHOOL CHEMISTRY. 

present in some of the most poisonous vegetable prin- 
ciples. 

43. Use.— Nitrogen is not only a diluent for oxygen 
in the atmosphere, but it plays a most important part 
in life. Plants can utilize many of the nitrogen com- 
pounds directly. There are germs in the soil which 
have the power of rendering nitrogen almost directly 
available to the plants. The free gas is not assimi- 
lated. 

44. Ammonia.— The first compound of nitrogen 
we shall study is the common substance, ammonia, a 
gas resulting from the union of three volumes of hy- 
drogen, with one of nitrogen. In desert countries, des- 
titute of trees, the natives in need of fires, use whatever 
fuel comes nearest to hand. The excrement of camels, 
the beasts of burden of some of these arid wastes, has 
long proved a profitable source of heat for cooking 
food. The Arabs, years ago, knew ammonia by the 
peculiar odor given off when this refuse, parched by 
the sun, was burned. This method of heating was 
practiced about the Temple of Jupiter Ammon, whence 
came the name, ammonia. 

45. Preparation. — As nitrogen and hydrogen com- 
bine directly only with difficulty, the best method of 
preparing ammonia is by heating ammonium chloride 
(sal ammoniac) with quick lime. 



NITROGEN — AMMONIA. 37 

46. Properties. — Ammonia is a colorless gas, 
lighter than the air, and possessing a strong, pungent 
odor. It is exceedingly soluble in water ; one part of 
cold water dissolves eight hundred times its volume, 
hence the gas cannot be collected over water, but by 
upward displacement. The water solution is our 
ordinary ammonia water or spirits of hartshorn, so 
named because it can be made by distilling the horns 
of the hart. The gas and its water solution turn red 
litmus paper blue, which is a characteristic of many 
basic substances. All ammonium salts are volatilized 
on the application of heat. 

47. Uses. — Ammonia has many uses in science and 
the arts. Scarcely a houskeeper can fail to tell one 
some of the many practical uses to which it is put, 
as cleaning silver, removing paint, washing windows, 
and so on. 

EXPERIMENTS. 

I. Place equal amounts, about 2 g. each, of sal ammoniac and 
quick lime in a test tube and heat gently. Note the odor of the 
gas evolved by fanning the fumes under the nose with the hand. 
Do not breathe too much of it. Moisten a piece of red litmus 
paper and hold it over the tube without allowing it to touch the 
glass. 

II. Open a bottle of strong ammonia (ammonium hydroxide) 
near a bottle of strong hydrochloric acid. The dense fumes are 
ammonium chloride, the material heated with the lime in Ex- 
periment I. 

III. Insert a cork with an exit tube, 10 c. m. long, in the tube 
used in Experiment I, and collect a test tube full of the gas by up- 



38 SCHOOL CHEMISTRY. 

ward displacement. Place the thumb over the open end of the tube 
used for collecting the gas, and plunge that end of the tube into 
water. On removing the thumb, what do you see ? 

IV. Place a small piece of ammonium chloride upon a piece of 
mica or platinum. Heat it over the flame. Kepeat the experi- 
ment, placing the sal ammoniac in a test tube and heating it. 



LESSON VIII. 



CHLORINE. 



48. Colored Gas. — So far in our studies we have 
had only colorless gases to deal with. Many gases are 
colored, and the one we learn of to-day is greenish- 
yellow. This gas, called chlorine, from a Greek word 
descriptive of its color, is conveniently prepared by 
heating strong hydrochloric acid with manganese diox- 
ide. Being soluble in water, and over twice as heavy 
as the air, it is collected by downward displacement. 

49. Properties. — It has a very disagreeable and 
irritating odor. It is poisonous when inhaled, and one 
must be careful not to breathe it. When absorbed by 
water, that liquid acquires a yellow tint. When mixed 
with hydrogen and exposed to the sunlight, or ignited , 
a violent explosion results, with the formation of the 
important compound already mentioned, hydrochloric, 
sometimes called " muriatic," acid. Since chlorine 
kills disease germs, it is used as a disinfectant. 



CHLORINE. 39 

50. Chlorides. — Many metals, as copper or anti- 
mony, combine directly with chlorine, burning with a 
bright flame. The compound formed is a chloride. 
On account of this affinity for metals, chlorine is never 
found free in nature, but always in combinations 
called chlorides ; for example, sodium chloride (com- 
mon salt). 

51. Bleaching. — Chlorine has such a strong affinity 
for hydrogen that it will decompose many bodies con- 
taining that element by combining with the hydrogen. 
Thus, with water, it forms hydrochloric acid and lib- 
erates free oxygen. Oxygen liberated in this manner 
possesses a peculiar power of destroying or changing 
many coloring matters. Oxygen, as ordinarily pre- 
pared, cannot do this. This extraordinary activity of 
oxygen is accounted for by assuming that it is in the 
nascent state ; that is, the state of being born. Now, 
the molecule of oxygen contains two atoms, which 
saturate one another, as it were ; part of the combin- 
ing energy of the atoms is used up in the union. 
Therefore, it is obvious that oxygen atoms not so satu- 
rated would possess more energy than otherwise, and 
this state of unsaturation exists before any union has 
occurred, or at the time of being born, so to speak. 
Many moist colors, as in leaves, flowers and inks, are 
bleached by this activity of chlorine in liberating 
nascent oxygen. If the substance be dry, no water 
being present to be decomposed, no bleaching results. 
Printer's ink is not decolorized, because it is mainly 



40 



SCHOOL CHEMISTRY. 



composed of minute particles of carbon, which are not 
affected by nascent oxygen. 

The most convenient form in which chlorine can be 
used for these purposes is in the compound " chloride 
of lime," or "bleaching powder," which is made by 
passing chlorine gas over lime. 

EXPERIMENTS. 

I. In apparatus shown in Fig. 5 place a teaspoonful of manganese 
dioxide, and cover the black powder with concentrated hydrochloric 
acid, shaking until thoroughly wet. Add as much more acid and 
warm gently. Collect the gas by downward displacement, resting 
the end of the exit tube upon the bottom of the bottle. When the 




Fig. 5. 



gas rises until it rolls over the edge of the mouth of the receiving 
bottle, remove, and cover with a piece of paper or glass plate. In 
this manner collect five dry bottles full of the gas, noting the color 
and choking odor. If a hood or a draught chamber be at hand, 



HYDROCHLORIC ACID. 41 

perform these experiments under it ; if not, work either out of 
doors, or where there is good ventilation, (a) In one bottle intro- 
duce with tweezers a piece of thin copper foil or Dutch leaf, (b) In 
another, drop a pinch of powdered antimony which has been 
heated upon the end of a knife blade, (c) In another, place a 
flower, a moist piece of paper upon which there is writing with ink 
and a wet piece of calico, (d) In the fourth, place a dry piece of 
the same calico. What conclusion do you draw from these last 
two experiments? (e) In the fifth, insert a piece of filter paper 
which has been moistened with turpentine. 

II. Place a teaspoonful of " bleaching powder " in a small 
beaker. Half fill the beaker with water. In a similar beaker, 
place an equal amount of dilute hydrochloric acid. Partially dip a 
strip of chocolate calico alternately in one and then the other 
several times. Finally wash the entire piece in clear water. 



LESSON IX. 

HYDROCHLORIC ACID. 

52. Gaseous Compounds. — We have gaseous com- 
pounds as well as gaseous elements, as we learned in 
the case of ammonia. Ammonia is a compound of 
hydrogen and nitrogen, possessing basic properties. 
To-day we have a compound containing hydrogen and 
chlorine, which is the very opposite of ammonia in 
being acid and not basic. It is hydrochloric acid. 

53. Preparation. — We may prepare this acid by 
heating ordinary cooking salt with sulphuric acid. 
This may be done in apparatus similar to that used for 
the preparation of chlorine (Fig. 5, p. 40). Hydro- 
chloric acid gas is given off and sodium hydrogen sul- 



42 SCHOOL CHEMISTKtf. 

phate remains behind as a crystalline compound in 
the flask. 

54. Properties.-^Hydrochloric acid is a colorless 
gas, heavier than the air. It has a choking odor, and 
produces coughing when breathed. Water dissolves 
about five hundred times its volume at 15 °C. The 
solution of the gas in water is what we usually see in 
drug stores and use in our experiments, and is sold as 
" muriatic acid." It is neither combustible nor a sup- 
porter of combustion. 

55. Solvent Action. — Hydrochloric acid dissolves 
many metals liberating hydrogen gas. It also dis- 
solves many oxides producing water and a chloride. If 
added to certain clear solutions, silver nitrate, for ex- 
ample, an insoluble solid is produced. For these rea- 
sons hydrochloric acid is not found free in nature. It 
does occur in small amount in the gastric juice of man 
and many animals. * 

56. General Properties of Acids. — As this is the 
first acid we have studied, we may learn something 
about the general class of bodies called Acids. All 
acids contain hydrogen combined with some other sub- 
stance ; for instance, hydrochloric acid contains hydro- 
gen and chlorine. Other substances may take the 
place of chlorine in hydrochloric acid, as, for instance, 
bromine or sulphur, but a different acid is formed in 
each case. Although all acids contain hydrogen, all 
compounds which contain hydrogen are not necessarily 



hydrochloric acid. 



43 



acids. Most acids, when diluted, possess a sour taste, 
and put the teeth on edge. Many of them are corro- 
sive poisons when strong — that is, concentrated. An 
acid is usually made dilute by adding water to the 
strong. Acids, as a rule, turn litmus, a vegetable col- 
oring matter, red. Bases, as we shall learn, turn lit- 
mus blue (§ 76). 

EXPERIMENTS. 

I. In apparatus similar to that shown in Fig. 5, place a teaspoon- 
ful of ordinary cooking salt and add enough concentrated sulphuric 
acid to cover the sodium chloride. Heat gently ; do not allow the 
froth to get up into the neck of the flask, (a) Note odor, (b) 
Expose a piece of moist blue litmus paper to the fumes, (c) Open 
i bottle of strong ammonium hydroxide and bring near the exit 
tube, (d) Collect a dry test tube full of the gas by downward dis- 
placement. Cover the tube with the thumb, and quickly invert 
in a pan of water and remove the thumb. The smoking of the 
acid in the air is due to its great attraction for moisture. 

II. In a test tube containing a little dilute hydrochloric acid 
drop a small piece of zinc ; in another, a pinch of magnesium ox- 
ide; in a third, a drop of silver nitrate solution. For comparative 
observations place tubes in rack (Fig. 6). Prepare dilute hydro- 
chloric acid by adding one part of concentrated acid to two of 
water. 




Fig. 6. 

III. To ten drops of water add one drop of dilute hydrochloric 
acid. Taste the liquid. Test it with blue litmus paper. 

If hydrochloric acid be accidentally dropped upon the clothing, 
add ammonium hydroxide to the spot and wash out. 



44 SCHOOL CHEMISTRY. 



LESSON X. 

COMPOUNDS OF NITROGEN AND OXYGEN. 
NITRIC ACID. 

57. Laughing Gas. — Nitrogen forms five con> 
pounds with oxygen. One called nitrogen monoxide, 
or nitrous oxide, is the "laughing gas" used by 
dentists to produce insensibility to pain in drawing 
teeth. Sir Humphrey Davy, an Englishman, was the 
first to prove the anaesthetic power of the gas. It may 
be prepared by carefully heating ammonium nitrate, 
and collecting the gas over warm water. The color- 
less gas is somewhat soluble in cold water and has a 
sweet taste. When sufficiently heated, it will support 
combustion. 

58. Other Oxides of Nitrogen. — Nitrogen diox- 
ide, or nitric oxide, is produced when fifty per cent, 
nitric acid acts upon metallic copper. It can be col- 
lected over water and is colorless. On exposure to 
the air, however, it immediately combines with oxygen 
to form the tri- and tetroxides of nitrogen, which 
are deep brown or red in color. The fifth, or pent- 
oxide of nitrogen, is a white solid. It dissolves in 
water to form nitric acid. All these oxides, except 
the monoxide, are poisonous. 

59. Nitric Acid was called aqua fortis by the old 
alchemists, who knew the substance only in an impure 
form. Many still use the name. It combines with 
metals and metallic oxides to form nitrates. The acid 



COMPOUNDS OF NITROGEN AND OXYGEN. 45 

is not formed in nature, but the nitrates are. Potas- 
sium nitrate is " saltpetre," used in making gunpowder, 
and sodium nitrate is " Chili saltpetre," used in fertil- 
izers. 

60. Preparation. — Nitric acid is prepared by dis- 
tilling a mixture of sodium nitrate and concentrated 
sulphuric acid. It is a colorless liquid when pure, 
quickly turning yellow under the influence of light, 
being thus easily decomposed, although it is one of the 
strongest acids. 

61 Properties. — Nitric acid is a very strong oxidi- 
zing agent, as we might suppose, when we learn that 
each molecule contains, besides one atom each of hy- 
drogen and nitrogen, three atoms of oxygen. The strong 
acid acts upon organic bodies, such as dry sawdust, 
generating heat sufficient at times to set fire to the 
substance. It colors the skin yellow. Silk and wool 
are sometimes dyed yellow by the action of nitric acid. 

EXPERIMENTS. 

I. A round-bottomed flask of 100 cc. capacity, provided with a rub- 
ber stopper and exit tube, is necessary. Place the flask in an iron 
clamp, and pour in a tablespoonful of ammonium nitrate. Heat 
cautiously, and collect the gas, which is nitrogen monoxide, in 
bottles over warm water. After noting odor and taste, insert a 
lighted match in one bottle of the gas ; in another suspend a small 
piece of burning phosphorus in a chalk cup. 

II. Place a teaspoonful of copper clippings in a flask provided 
with stopper and exit tube (Fig. 3.) Pour in 5 cc. concentrated 
nitric acid diluted with an equal amount of water, and collect 
several bottles of the gas over water Use water bottle (Fig. 7) for 
diluting. It should be colorless when collected. Place a glass 
plate under the last bottle, and raise it from the water j invert 
and remove the plate. Explain, 



46 



SCHOOL CHEMISTRY, 




Fig. 7. 

III. Put a handful of dry sawdust in a collar box, and pour a 
tablespoonful of strong nitric acid on it and allow it to stand. Per- 
form this experiment out of doors. 

IV. Dip a piece of clean wool for about one minute into concen- 
trated nitric acid. Eemove and wash. 



LESSON XI. 



CARBON. 

62. Allotropism. — So far we have had only one 
case of an element existing, as an element, in more 
than one form, and that was the gaseous element 
oxygen. Now we have an element — carbon — which 
exists in at least three distinct modifications. The 
diamond and graphite varieties are crystalline, while 
the third form, comprising many subvarieties, is amor- 
phous — that is, without crystalline structure, 



CARBON. 47 

63. Artificial Diamonds. — Diamonds are found in 
South Africa, Brazil and India, usually in a blue 
cement rock, which fills the craters of extinct vol- 
canoes. They also occur in alluvial deposits from the 
oldest rock formations. Very small diamonds have 
been artificially produced recently by an eminent 
French chemist, Moissan, by dissolving carbon in 
molten iron, and subjecting this to pressure as it cooled. 
Diamonds fuse at about 3000° C. We know of no 
substance which cannot be melted at that extremely 
high temperature. 

64. Jewels. — The diamond, as it is found in nature, 
resembles very much an ordinary quartz pebble, and 
is not at all like the beautiful gem we see in the 
jewelry shops. It has been cut and polished to present 
a brilliant and attractive appearance. It is one of the 
hardest known substances. 

65. Plumbago. — Graphite, often called plumbago 
or black lead, is found in Ceylon, Siberia and the 
United States. It is black and lustrous, and has a 
greasy feel. It makes a black mark upon paper, and 
is used as a stove polish, in making crucibles, and as 
a lubricant for machinery. Bicycle chains are " oiled " 
with powdered graphite mixed with vaseline. Lead 
pencils are made by grinding the graphite to a fine 
powder, washing and pressing it into proper shape to 
fit the wooden case. Clay in varying proportions is 
mixed in with the graphite to produce the different 
degrees of hardness of the pencils. 

66. General Properties. — Carbon is heavier than 



48 SCHOOL CHEMISTRY. 

water, almost infusible, and insoluble in all known 
liquids except molten iron. Melted iron can dissolve 
about five per cent, of carbon, but, on cooling, some of 
it separates out in the form of graphite. The forms 
of carbon vary in their ability to conduct electricity. 
Graphite is the best conductor, and, in the form of 
powder, is much used in electro-plating. All forms of 
carbon, when heated in an atmosphere of oxygen, burn 
with the formation of carbon dioxide. 

67. Amorphous Varieties. Artificial. — Char- 
coal is made by the dry distillation of wood ; that is, 
the wood is heated without the presence of air. Char- 
coal is heavier than water, although it is the lightest 
form of carbon. Freshly heated charcoal absorbs 
large quantities of such gases as ammonia, oxygen 
and sulphuretted hydrogen ; therefore it is frequently 
used to disinfect places that emit offensive odors. 
Really, it is merely a deodorizer. 

68. Coke is made by heating bituminous coal to 
red heat without the presence of air. It is used in the 
manufacture of iron. Lamp black is ordinary soot, 
which, mixed with boiled linseed oil and a little soap, 
is used as printer's ink. Bone black is made by 
heating bones to red heat without the presence of air. 
It consists of only about ten per cent, of carbon, the 
rest being bone ash (calcium phosphate). 

69. Natural. — Coal contains carbon, hydrogen, 
oxygen, and small quantities of sulphur and nitrogen, 
along with silica. It is said to be the result of the 
partial decay of organic matter in nature, at the same 



CARBON. 



49 



time having been subjected to great pressure, and pos- 
sibly heat, in certain cases. The purest form of coal 
is anthracite or hard coal. The next in order of 
purity is the bituminous or soft coal. Cannel and 
brown coals contain even more oxygen and hydrogen. 
Peat is only partially decomposed swamp moss. 

EXPERIMENTS. 

I. Put some fragments of wood in a test tube, and heat the tube 
until no more gas is given off. The best grade of charcoal is pre- 
pared by heating wood in closed iron retorts, the gases being 
allowed to escape through a pipe. 




^ 



^ Q •• c> ^ 



?/. 



3=3> 



Fig. 8. 

II. Compare the combustibility of charcoal and graphite by 
heating them separately upon a small piece of platinum. 

III. Throw a piece of charcoal upon water ; it floats. Heat a 
similar piece quite hot and plunge it suddenly under the water ; it 
sinks. Why do you heat the charcoal ? 

IV. Fill a test tube one-third full of water ; add several drops of 
ink, and then some coarsely powdered bone-black. Place the 
thumb over the mouth of the tube, shake vigorously, and filter. 
Repeat the experiment, substituting a solution of brown sugar. 
To filter, fold a round piece of porous paper, as shown in Fig. 8, 
and fit it snugly in a funnel. Wet with water, and pour the solu- 
tion into the funnel. 



50 SCHOOL CHEMISTRY. 

LESSON XII. 

NOMENCLATURE. CHEMICAL EQUATIONS. 
VALENCE. 

70. Elements. — So far, we have studied five differ^ 
ent kinds of elementary matter — hydrogen, oxygen, 
nitrogen, carbon and chlorine. There are about 
seventy different kinds of elementary substances known 
to chemists. These substances have never been de- 
composed into anything else ; they may be some day. 
Some new elements may be discovered that will have 
to be added to the list, which is shown on the next 
page. These elements have different and fixed atomic 
weights as shown in the table. As we learned before, 
hydrogen is the lightest substance known to chemists, 
hence it is taken as the standard of atomic weights ; 
that is, if a liter of hydrogen weighed one gram, a liter 
of oxygen would weigh sixteen grams, if the gases 
were under equal pressure, and at the same tempera- 
ture. In most instances, the names of the elements 
were given them by their discoverers. The name was 
sometimes selected to denote a peculiarity the element 
possessed, or to indicate the source from which it can be 
derived, and in other cases the name is the legacy from 
the alchemist, and is apparently without meaning. 

71. Symbols. — In arithmetic, we use figures to indi- 
cate numbers. In a similar way, in chemistry, we use 
a symbol to designate the element. It is merely a 
convenience in denoting the element without writing 
out the whole name. The initial letter of the Latin 



NOMENCLATURE. CHEMICAL EQUATIONS. 51 

name is the usual symbol, though not always, as K. 
for kalium (Latin for potassium), or H. for hydro- 
genium. Where there are several having the same 
initial letter, one of the elements is given the initial 
letter for its symbol, and each of the others adds 
another letter from its name to the initial letter for 
its symbol, as C. for carbon, CI. for chlorine, Cu. for 
cuprum or copper. The initial letter is always written 
with a capital and the other a small letter. In writing 
a, compound we allow the symbols of the elements to 
follow one another in regular order, as HC1. for hydro- 
chloric acid. Such a formula represents the composi- 
tion of one molecule of the compound. When an ele- 
ment enters more than once into a compound — i. e., 
has more than one atom in the molecule of the com- 
pound — we designate its repetition by a small numeral 
below, and to the right of the symbol, as H 2 instead 
of HHO, or HN0 3 for HNOOO (nitric acid). When 
the whole compound is taken several times, it is so 
stated by a numeral just before the symbols, indicating 
the compound as 4HC1, or 5NH 3 (ammonia). Do 
not mistake the memorizing of a lot of symbols for 
learning chemistry. A thorough knowledge of them 
will prove of great assistance, but it is not absolutely 
essential. 

72. Valence. — Chlorine, we remember, combines 
with only one hydrogen atom forming hydrochloric 
acid (HC1) ; oxygen with two in water (H 2 0) ; nitro- 
gen with three in ammonia (NH 3 ) ; and our last ele- 
ment, carbon, combines w T ith four hydrogen atoms in 



52 SCHOOL CHEMISTRY. 

the compound methane (CH 4 ), which we have not yet 
studied. If we arrange them in order, making use of 
the symbols, we have : 

C1H . . . OHH .... NHHH .... CHHHH. 

The number of hydrogen atoms entering into these 
compound is 1, 2, 3, and 4 ; so we may say that the 
value, as we may term it, of chlorine in hydrogen 
atoms is one, of oxygen two, of nitrogen three, and of 
carbon four. One atom of chlorine is combined with 
one atom of hydrogen, therefore we may say that they 
have the same value. Suppose a hydrogen atom be 
represented by a nickel, and a chlorine atom by a sil- 
ver five cent piece. They have the same value. Now 
if an oxygen atom be represented by a dime, we know 
that it is worth two nickels or silver five cent pieces. 
Exactly ; oxygen combines with two atoms of hydro- 
gen in water (H 2 0) and two of chlorine in chlorine 
monoxide (C1 2 0). Nitrogen may be regarded as 
worth fifteen cents in terms of nickels, NH 3 (am- 
monia), or silver five cent pieces, NC1 3 (nitrogen 
trichloride), or one dime and a nickel, (NOH) (hy- 
ponitrous acid). Further, if carbon be put at twenty 
cents, it may be worth four nickels, (CH 4 ) (methane), 
or four silver five cent pieces (CC1 4 ) (carbon tetrachlo- 
rides), or part of one and part of the other, as CH 3 C1, 
CH 2 C1 2 , CHC1 3 (chloroform). To carry this a little 
further, an oxygen atom, a dime, may be exchanged 
for two nickels or silver five cent pieces, and we have 
COH 2 (formaldehyde), or it may be expressed in 
terms of dimes, for CH 4 we have C0 2 (carbon dioxide). 



NOMENCLATURE. CHEMICAL EQUATIONS. 53 

This property of elements is termed valence or ato- 
micity, hence chlorine is univalent, oxygen bivalent, 
nitrogen trivalent and carbon quadrivalent, the Latin 
prefixes being used to designate the figures. Valence 
is merely the expression of the value of chemical 
affinity, without regard to its strength. 

73. Chemical Equations. — When we wish to write 
out the effect of one chemical upon another, we use 
the symbols, placing them exactly as if they were in 
an algebraic equation. It is a very great saving to 
use the following : 

HC1 + NaOH = NaCl + H 2 0, 

instead of writing out that " hydrochloric acid acting 
upon sodium hydroxide produces sodium chloride and 
water." Now, then, we notice that if we take the 
atomic weights corresponding to these elements and 
place them in an equation, the sums of the numbers 
on each side of the equality marks are equal, as should 
be. In all chemical equations this is one of the proofs 
of accuracy. 

H CI + Na H = Na CI + H 2 
(l + 35.5) + (23 + 16 + l)=(23 + 35.5) + (2 + 16)=76.5. 

It is a little trying at first to memorize any of these 
symbols, but it becomes quite easy with practice. 

EXPERIMENTS. 

I. Place equal amounts of powdered sulphur and iron filings in 
tube, about half a teaspoonful each, and heat to dull red heat for 
ten minutes. Allow to cool and save. 



54 SCHOOL CHEMISTRY. 



TABLE OF ELEMENTS, THEIR SYMBOLS AND ATOMIC 
WEIGHTS. 

From the latest report (1898) of Prof. F. W. Clarke, Chairman of 
the Committee on Atomic Weights, American Chemical Society. 

Name of Element. Symbol. Atomic "Weight. 

Aluminum Al. 27.11 

Antimony (Stibium) Sb. 120.43 

Argon A. ? 

Arsenic As. 75.01 

Barium Ba. 137.43 

Bismuth Bi. 208.11 

Boron B. 11.95 

Bromine Br. 79.95 

Cadmium Cd. 111.95 

Calcium Ca. 40.07 

Carbon C. 12.00 

Cerium Ce. 139.35 

Cesium Cs. 132.89 

Chlorine CI. 35.45 

Chromium Cr. 52.14 

Cobalt Co. 58.99 

Columbium Cb. 93.73 

Copper (Cuprum) Cu. 63.60 

Erbium Er. 166.32 

Fluorine Fl. 19.06 

Gadolinium Gd. 156.76 

Gallium Ga. 69.91 

Germanium Ge. 72.48 

Glucinum Gl. 9.08 

Gold (Aurum) Au. 197.23 

Helium He. ? 

Hydrogen H. 1.00 

Indium , In. 113.85 

Iodine. I. 126.85 

Iridium Ir. 193.12 

Iron (Ferrum) Fe. 56.02 

Lanthanum La. 138.64 

Lead (Plumbum) Pb. 206.92 

Lithium j Li. 7.03 



TABLE OF ELEMENTS. 55 

Magnesium Mg. 24.28 

Manganese Mn. 54.99 

Mercury (Hydrargyrum) Hg. 200.00 

Molybdenum Mo. 95.99 

Neodymium Nd. 140.80 

Nickel Ni. 58.69 

Nitrogen N. 14.04 

Osmium Os. 190.99 

Oxygen O. 16.00 

Palladium Pd 106.36 

Phosphorus P. 31.02 

Platinum Pt. 194.89 

Potassium (Kalium) K. 39.11 

Praseodymium Prd. 143.60 

Rhodium Rd. 103.01 

Rubidium Rb. 85.43 

Ruthenium Ru. 101.68 

Samarium Sa. 150.26 

Scandium Sc. 44.12 

Selenium Se. 79.02 

Silicon Si. 28.40 

Silver (Argentum) Ag. 107.92 

Sodium (Natrium) Na. 23.05 

Strontium Sr. 87.61 

Sulphur S. 32.07 

Tantalum Ta. 182.84 

Tellurium Te. 127.49 

Terbium Tb. 160.00 

Thallium Tl. 204.15 

Thorium * Th. 232.63 

Thulium Tu. 170.70 

Tin (Stannum) Sn. 119.05 

Titanium Ti. 48.15 

Tungsten (Wolfram) W. 184.83 

Uranium. U. 239.59 

Vanadium V. 51.38 

Ytterbium Yt. 173.19 

Yttrium Y. 89.02 

Zinc Zn. 65.41 

Zirconium Zr. 90.40 



56 SCHOOL CHEMISTRY. 



LESSON XIII. 



ACIDS. BASES. COMPOUND RADICALS. 
SALTS. 

74. Acid and Basic Oxides. — All the elements 
mentioned in the table except a few, argon, neon, cryp- 
to^ metargon (all recently discovered), helium, bro- 
mine, and fluorine, combine with oxygen to form 
compounds termed oxides. If the oxide combines 
with water to form an acid compound, as sulphur tri- 
oxide (SO 3 ), we have an acid forming oxide. If the 
compound formed is a base, as sodium monoxide 
(Na 2 0) and water, we have a basic oxide. 

75. Electric Conduct. — There are many substances 
that are decomposed by the electric current. These are 
called electrolytes. That portion of the substance 
which separates at the positive pole (see note, § 25, 
Lesson IV) is termed electro-negative, and that separa- 
ting at the negative pole, electro-positive. As we 
learned that water is one of those substances we shall 
use it as our type, by which we may better understand 
the terms acid and base. 

76. Base. — The formula for water may be written 
in this wise : H-O-H. Hydrogen is electro-positive, 
as we have learned. All the metallic elements are, as 
a rule, more strongly electro-positive than hydrogen, so 
we may substitute one of them ; for example, sodium, 
for a part of the hydrogen in w T ater, and obtain Na-0-H ? 
which is a base, or hydroxide. The bases are opposed 



ACIDS. BASES. COMPOUND RADICALS. 57 

to acids, we may say, as some of them turn litmus paper 
blue, while the acids, as a rule, turn it red. 

77. Compound Radicals. — There are certain com- 
pounds which withstood for a long time all efforts made 
by chemists to decompose them. They acted very 
much like elements, but were eventually proven to be 
compounds instead. Substances of compound nature 
acting much like elements under ordinary circum- 
stances, but capable of decomposition, are called com- 
pound radicals. Ammonium (NH 4 ) is one, and it may 
be substituted for the hydrogen in water as well as an 
element, so we have NH 4 -0-H. Therefore, a base 
may be regarded as water in which one hydrogen atom 
has been substituted by an electro-positive element or 
radical. 

78. Acid. — Now suppose we substitute the -O-H, 
called hydroxyl, by an electro-negative element or 
radical ; for example, chlorine, we have HC1, or by 
-NO 3 , when we have HN0 3 (nitric acid). Thus we 
see that an acid may be regarded as water in which the 
hydroxyl has been substituted by an electro-negative 
element or radical. 

79. Salts. — Bring together an acid and a base, as 
sodium hydroxide and hydrochloric acid or ammonium 
hydroxide and nitric acid, and we have a salt produced 
and water formed. The equations are as follows : 

Base. Acid. Salt. Water. 

NaOH + HC1 = NaCl + H 2 0, and 

Base. Acid. Salt. Water. 

NH 4 OH + HN0 3 = NH 4 N0 3 + H 2 0. 



58 SCHOOL CHEMISTRY. 

Such a compound is a salt. Salts, as a rule, are 
neutral towards litmus paper, but not always so. Some 
are soluble in water, and each possesses its own peculiar 
taste. Some are insoluble in water and also in acids. 
The result of the union of an acid forming oxide and 
a base forming oxide is likewise a salt. Example : 

Salt. 
SO 3 + Na 2 = Na 2 S0 4 . No water is eliminated in 

this case, however. 

80. Chemical Terms. — When we separate a com- 
pound into its constituents, as by the action of sodium 
upon water, we call it analysis. If we combine ele- 
ments • to make a compound, as in burning hydrogen 
in oxygen to produce water, we call it synthesis or 
building up. If an interchange of the elements of 
two compounds takes place to produce two new com- 
pounds, as shown above in the formation of salts from 
acids and bases we have metathesis, or double de- 
composition. 

EXPERIMENTS. 

I. In a porcelain evaporating dish pour 5 cc. of a dilute (about 
ten per cent.) solution of NaOH. "While stirring add to it dilute 
HC1 until a piece of litmus paper is no longer turned blue by a 
drop of the solution placed upon it with a glass rod. If the solu- 
tion finally turns the paper red, add a little more of the NaOH so- 
lution. Repeat, adding first one and then the other until the litmus 
paper is no longer affected by the solution. Evaporate most of the 
liquid by heating over a lamp and allow to cool. State what takes 
place, writing equation, giving reason for evaporating, and finally 
taste the substance obtained. 

II. Repeat the first experiment, using ammonium hydroxide and 
nitric acid, instead of sodium hydroxide and hydrochloric acid. 



CARBON MONOXIDE AND DIOXIDE. 59 



LESSON XIV. 

CARBON MONOXIDE AND DIOXIDE 

81. Carbon Monoxide. — Carbon forms two com- 
pounds with oxygen, carbon monoxide (CO) and car- 
bon dioxide (C0 2 ). Carbon monoxide is a colorless, 
odorless gas, which burns with a pale, blue flame. The 
lambent blue flame hovering over ignited anthracite 
coal is caused by the burning of this compound to 
form the higher oxide, carbon dioxide. The monoxide 
is very poisonous, and is a prominent constituent of 
" w T ater gas." Water gas is produced by passing steam 
over very hot coke. The water is decomposed into 
free hydrogen, and the oxygen unites with carbon to 
form the monoxide. This kind of gas burns with a 
non-luminous, but intensely hot, flame. 

82. Law of Multiple Proportions. — You remem- 
ber that we learned that a chemical compound always 
has the same elements entering into it in the same pro- 
portion. We also learned that nitrogen forms five 
different compounds with oxygen ; they have the same 
elements entering into them, but in different propor- 
tions. We have a similar case to-day with carbon. 
We have the monoxide and the dioxide. There is a 
law in chemistry that when one element combines 
with the same element in different proportions to form 
different compounds, the amounts of the varying ele- 
ment bear the relation of simple multiples to each 
other. For instance, CO and C0 2 have oxygen, the 



60 SCHOOL CHEMISTRY. 

varying element, present in the ratio of 1 : 2 ; again 
with the oxides of nitrogen, we have N 2 0, N 2 2 , 
N 2 3 , N 2 4 and N 2 5 , that is, 1 : 2 : 3 : 4 : 5. 

83. Carbon Dioxide. — Carbon dioxide (C0 2 ) is 
also a colorless, odorless gas. It is produced when 
carbon is burned in an excess of oxygen or air. The 
gas given off from the flame of a candle or a lamp is 
carbon dioxide, as may be shown by passing the gas 
through lime water. The white solid substance, which 
is precipitated, is calcium carbonate (Ca C0 3 ). When 
two clear solutions are brought together and a solid is 
produced, we say it is " precipitated." 

84. Result of Oxidation. — Carbon dioxide is given 
off by the lungs in breathing. Its formation is due to 
the oxidation of the carbon in organic substances in 
the body by the oxygen which is breathed into the 
lungs. Carbon dioxide does not support combustion, 
nor does it burn when fire is applied to it. It cannot 
support life. An animal would die of suffocation if 
allowed to breathe nothing but carbon dioxide ; it is 
not poisonous, however. 

85. Properties — Carbon dioxide is slightly soluble 
in cold water, but more soluble when under pressure, 
forming what is known as soda water. The solution 
is called " carbonic acid water," but is really carbonic 
acid in solution. C0 2 combines with H 2 to produce 
the hypothetical carbonic acid (H 2 C0 3 ), for it has 
never been separated. Carbon dioxide may be lique- 



CAHfeoN Monoxide and dioxide. 61 

fied by great pressure, and is transported in that form 
in iron cylinders. When this liquefied gas is allowed 
to evaporate quickly, intense cold is produced, suffi- 
cient not only to freeze water and mercury, but to 
cause some of the carbon dioxide itself to be solidified 
into a snow-like mass. 

86. Heavier than Air. — It is half again as heavy 
as air, and should be collected by downward displace- 
ment. The gas can be poured from one vessel into 
another like water, only we do not see the gas as we do 
the water. Being heavier than the air, this gas, when 
liberated in large quantities, as it is by some volcanoes, 
settles down in valleys and remains there, unless dis- 
turbing winds displace it. Several places of this kind 
are known, and are termed " Death Valleys." 

87. Wide Distribution. — All combustible material 
containing carbon, which burns, produces carbon diox- 
ide, thus a great deal of this gas must be given off 
every hour of the day by the huge furnaces and forest 
fires. Although the quantity thus produced is enor- 
mous, it seldom constitutes in any locality more than 
about four parts in ten thousand of the atmosphere ; 
yet that amount, the volume of the atmosphere being 
so great, is more than would be produced if the result 
of the combustion of all the vegetable and animal 
matter in the world were uniformly distributed 
throughout the air. 

88. Preparation. — Carbon dioxide is most easily 
prepared for experimental purposes by treating calcium 



62 



School chemistry. 



carbonate (common marble or limestone) with dilute 
hydrochloric acid. 

EXPERIMENTS. 

I. Prepare a small bottle of oxygen. Ignite a splinter of char- 
coal bound to a wire, and insert in the bottle. Remove after the 
combustion has ceased and introduce a stirring rod moistened 
with clear lime water. Do not touch the sides of the vessel with 
the rod. 

II. Set up apparatus like that shown in Fig. 9. Gently suck the 
short tube, holding the funnel over a burning candle or lamp. 
What is the white precipitate ? 




Fig. 9. 

III. Put a dozen pieces of marble in apparatus like that shown 
in Fig. 5. Add HC1. Try to set fire to the gas evolved. Test 
some with lime water. Collect a large bottle full of the gas 
and pour it into a wide mouth vessel containing a short, lighted 
candle. 



SULPHUR. HYDROGEN SULPHIDE. 63 



LESSON XV. 

SULPHUR. HYDROGEN SULPHIDE. 

89. Brimstone. — So far we have discussed but 
one solid element, and that one is usually colorless. 
To-day we have a yellow element. Sulphur occurs 
free in nature around volcanoes as Mt. Etna, in Sicily, 
and elsewhere. It has been known for centuries as 
" brimstone," having been found in large quantities 
near the Italian and Sicilian volcanoes. It also occurs 
in large amounts combined with iron, forming a com- 
mon mineral, iron pyrites, or " fool's gold " ; also as 
galena, a sulphide of lead (which is an important ore), 
and in similar compounds. 

90. Properties. — Sulphur is a yellow brittle solid, 
which melts a little above the boiling point of water 
to a clear yellow liquid. On further heating the light 
liquid changes to a red viscous mass, which, on further 
heating, liquefies again before it boils. It boils just 
like water, only at a very much higher temperature, 
440°C. 

91. Varieties. — Sulphur exists in two main forms, 
crystalline and amorphous. The ordinary sulphur, 
moulded in sticks, called "roll sulphur," and the 
powdered form, "flowers of sulphur," are crystallized. 
If we add a strong acid to a solution of a soluble sul- 
phide, as of potassium, we get a milky liquid. This 
milkiness is due to finely divided sulphur, the amor- 



64 SCHOOL CHEMISTRY. 

phous variety. Sulphur is insoluble in water, but 
most of its varieties are soluble in a compound of car- 
bon and sulphur, called carbon di-sulphide. 

92. Amorphous. — If we heat sulphur in a test tube 
until it becomes a dark red liquid, and quickly pour it 
into cold water, it assumes an India rubber appearance. 
This is also an amorphous form of sulphur, called 
"plastic sulphur." It changes to the crystalline vari- 
ety when kept for awhile however. 

93. Compounds. — Sulphur burns with a blue flame, 
noticed in sulphur matches. The disagreeable smelling, 
colorless gas given off is an oxide of sulphur, the diox- 
ide (S0 2 ), commonly, but incorrectly, called sulphurous 
acid. The compound of sulphur with hydrogen is 
hydrogen sulphide, commonly called sulphuretted hy- 
drogen. 

94. Sulphuretted Hydrogen. — If we heat a mix- 
ture of iron filings and sulphur in a tube to a low red 
heat, we cause the sulphur and iron to combine, form- 
ing a sulphide. Allow the tube to cool and add an 
acid, hydrochloric for example, to this black solid, and 
a gas will be given off. This gas has a very disagree- 
able odor ; in fact, the bad odor of rotten eggs is due 
largely to hydrogen sulphide (H 2 S). 

95. Sulphides. — Sulphuretted hydrogen burns with 
a pale blue flame. When the gas is passed through 
acid solutions of many metallic salts, as of copper, arse- 
nic, and lead, the sulphides of these metals are formed. 



SULPHUR. HYDROGEN SULPHIDE. 65 

The sulphides have various colors, hence their produc- 
tion serves as tests for the presence of certain metals. 

96. Sulphur Waters. — Sulphuretted hydrogen is 
quite soluble in water, the solution being prepared by 
bubbling the gas through pure water about ten min- 
utes. The waters of sulphur springs contain this 
gas in solution. On shaking with air the H 2 S is de- 
composed with the formation of free sulphur and water. 
Many tons of sulphur are annually produced artificially 
by decomposing the sulphuretted hydrogen obtained 
from calcium sulphide, a by-product in the manufacture 
of soda by the LeBlanc process, which we shall study 
later. 

97. Similarity to Water. — Under certain circum. 
stances sulphur has the same valency as oxygen. One 
volume of gaseous sulphur combines with two of hy- 
drogen to produce sulphuretted hydrogen, hence its 
formula is H 2 S. The sulphur seems to take the place 
of oxygen in water, H 2 0, hence it is bivalent. Again, 
carbon disulphide has the formula CS 2 exactly like 
carbon dioxide, C0 2 . Oxygen and sulphur resemble 
each other chemically very much, though physically 
there is no resemblance. 

EXPERIMENTS 

I. Burn a small piece of sulphur on a piece of porcelain. Note 
color of the flame and odor of the gas given off. 

II. Melt a spoonful of sulphur in a test tube. Note all the 
changes carefully. When the melted sulphur has become deep 
red, quickly pour it into a glass of cold water Examine it closely 
with eye and hand. 



66 



SCHOOL CHEMISTRY. 



III. Dissolve a little sulphur in some CS 2 and pour it out into an 
open vessel and allow the light liquid to evaporate. 

IV. Place some of the ferrous sulphide prepared in Lesson XII. 
in bottle " a," Fig. 10, and add 30 cc. dilute hydrochloric acid. In 
bottle " b " have pure water. After the gas has bubbled for five 
minutes allow the gas from tube " c " to bubble in turn through test 
tubes containing acidified water solutions of copper sulphate, lead 
nitrate, antimony potassium tartrate, and sodium arsenite. 




Fig. 10. 

Note.— Perform all experiments with this gas under a hood or in the open 
air. Dissolved in water the gas has the name of hydrosulphuric or sulph- 
hydric acid. Although the gas is poisonous when breathed, its water solu- 
tion is an efficacious remedy when taken internally. 

V. After smelling the water solution prepared in Experiment 
IV., test it with blue litmus paper ; then shake violently a little of 
the solution in a stoppered bottle. 



LESSON XVI. 



SULPHUR DIOXIDE. SULPHURIC ACID. 

98. Sulphur Dioxide. — Sulphur burns in the air 
or oxygen to produce a gas possessing a suffocating 
and irritating odor. This is sulphur dioxide (S0 2 ), 
and is soluble in water, the solution being called sul- 



SULPHUR DIOXIDE. SULPHURIC ACID. 67 

phurous acid (H 2 S0 3 ). The gas is not combustible, 
nor a supporter of combustion, and is poisonous to 
both animals and plants. As there is much sulphur 
in some of the bituminous coals, a great amount of 
sulphur dioxide is setfit out in the air where such coals 
are burned. It is washed down by the rains, and 
causes great damage to growing plants. In Cleveland, 
Ohio, over nine thousand tons of this gas are liberated 
in the air every year. Sulphur dioxide can be best 
prepared in the laboratory by heating concentrated 
sulphuric acid with metallic copper. 

99. Bleaching. — Sulphur dioxide destroys certain 
vegetable colors, and is used for bleaching straw from 
which hats are made. Its action, which requires the 
presence of water, is only temporary, however, as 
straw hats usually turn yellow on exposure. As it 
kills the disease-producing germs, it is used a great 
deal in disinfecting houses where infectious diseases 
have existed. 

100. Sulphuric Acid. — Sulphur dioxide can be 
made to unite with another atom of oxygen, producing 
sulphur trioxide (S0 3 ), which is very soluble in water. 
This solution is sulphuric acid, which, in concentrated 
form, is commonly called "oil of vitriol" (H 2 S0 4 ), 
because it was originally made from green vitriol, an 
iron sulphate (our ordinary copperas). 

101. Immense Amounts Used. — The method of 
manufacturing sulphuric acid is quite complicated. 
Large amounts of the acid are manufactured, the 



68 SCHOOL CHEMISTRY. 

United States yielding alone about nine hundred thou- 
sand tons annually. The financial and commercial 
progress of a nation may be judged by the yearly pro- 
duction of sulphuric acid. There is hardly a substance 
that we make use of in daily life — food, clothing, or 
what not — that is not directly or indirectly dependent 
upon the use of sulphuric acid in its production. 

102. Properties. — Sulphuric acid is a heavy, oily, 
colorless liquid when pure, and is soluble in water in 
all proportions. Ordinary sulphuric acid is colored 
brown on account of impurities present, some of which 
are lead, arsenic, organic matter, and the oxides of 
nitrogen. On mixing the ordinary concentrated acid, 
ninety-five per cent., with water, an immense amount 
of heat is developed. Great care should be exercised 
in mixing. The acid should always be slowly poured 
into and well stirred with the water, and never the 
reverse. 

103. Attraction for Water. — The concentrated 
acid greedily absorbs water from all substances. It 
has such a strong affinity for water that it will decom- 
pose sugar to get the water from it, and leave only 
black carbon behind. The acid acts upon all organic 
substances, which it attacks by taking water away 
from them. It blisters the skin. It is sometimes used 
by criminals to injure their enemies. 

EXPERIMENTS. 

I. Burn some sulphur under a large, colorless, bottomless bottle, 
within which are some moist, bright- colored flowers (Fig. 11). 



PHOSPHORUS. BASICITY OE ACIDS. 



69 




Fig. 11. 

When the experiment is completed, note the odor of the gas and 
test its combustibility. Next, remove the cork and insert a glass 
rod, to which is bound a tuft of cotton saturated with concentrated 
nitric acid. State your conclusion. 

II. Place 30 c. c. water in a beaker. A thick walled vessel will 
not do. Add, in a fine stream, 70 c. c. of concentrated sulphuric 
acid, stirring with a test tube half filled with alcohol, which has 
been colored with a little ink. 

III. Dip a splinter of wood into concentrated sulphuric acid for 
a few seconds. 

IV. Make a thick syrup by dissolving sugar in water in a test 
tube. Cool, and carefully add concentrated sulphuric acid. 

V. Use a glass stirring rod for a pen, and write upon filter paper 
with concentrated sulphurie acid for ink. 



LESSON XVII. 



PHOSPHORUS. BASICITY OF ACIDS. 

104. To-day we have an element which is so de- 
voted to oxygen that it is never found in nature unless 
combined in some way with that element. So we do 
not find phosphorus free, but as phosphates in bones 



70 SCHOOL CHEMISTRY. 

of animals and in certain phosphate rock. These 
phosphates always contain calcium, besides phos- 
phorus and oxygen, along with some iron and alumi- 
num. Large deposits of this rock are found, mined, 
and used as fertilizers. Phosphates in very small 
Amounts, however, occur in all kinds, and is an essen- 
tial constituent, of fertile soil. Most iron ores contain 
phosphorus also ; some contain it in notable amounts. 
Like carbon, sulphur and oxygen, phosphorus exists 
in allotropic forms. 

105. White Variety. — Ordinary phosphorus is a 
Very dangerous substance to have anything to do with. 
It is prepared from bones by a complicated process. 
Pure phosphorus is waxy and almost colorless, but the 
kind usually seen, is more or less yellow in color, and 
frequently contains some arsenic and carbon as im- 
purities. Waxy phosphorus is soluble in carbon 
disulphide, and oxidizes in the air, often melting and 
taking fire spontaneously, giving off white fumes pos- 
sessing the odor of garlic. To prevent this oxidation, 
phosphorus, usually in stick form, is kept under water. 
It may be cut with a knife, and it should never be 
handled with the hands except under water. It is ex- 
ceedingly poisonous, being used for a rat poison and to 
make matches. Phosphorus burns are intensely pain- 
ful and difficult to heal. Bathe the parts as soon as 
possible after phosphorus burning with a solution of 
blue stone, copper sulphate This is only effective 
when some of the phosphorus is left unburned. 



PHOSrHORUS. BASICITY OF ACIDS. 71 

106. Insoluble Form. — Red phosphorus is another 
variety, the harmless kind, made by heating the waxy 
form in an atmosphere of nitrogen free from oxygen. 
It is red in color, insoluble in carbon disulphide ; does 
not oxidize rapidly at the ordinary temperatures, and 
may be kept in a bottle without water. It is not 
poisonous, and does not take fire by friction, as does 
the waxy phosphorus. However, when heated to a 
high temperature, it changes back into the white form 
and takes fire at once. These allotropic forms of phos- 
phorus have the most widely divergent properties. 

107. Oxides. — Phosphorus forms several compounds, 
with hydrogen and oxygen. The former are very 
poisonous, and take fire spontaneously. Phosphorus 
trioxide (P 2 3 ), is formed by the slow oxidation of 
phosphorus, as when ozone is prepared. Phosphorus 
pentoxfde (P 2 5 ) is produced when phosphorus burns 
rapidly, or with an excess of air. It is a white solid, 
possessing the most intense attraction for water, phos- 
phoric acid (H 8 P0 4 ) resulting on solution. 

108. Phosphates. — The salts of phosphoric acid, 
called phosphates, are formed by the replacement of 
the hydrogen of the acid by metals. The important 
ones are calcium phosphate (bone phosphate), super- 
phosphate, and the sodium and ammonium phos- 
phates. Phosphates are the principal constituents of 
fertilizers. 

109. Basicity of Acids. — There are acids, hydro- 
chloric for instance, which contain no oxygen, but 



72 SCHOOL CHEMISTRY. 

many acids have that element in them. At one time> 
it was thought that all acids contained oxygen, there- 
fore, that element received its name from the Greek, 
meaning " acid producer." On adding water to the 
acid forming oxides, as we have learned, we obtain 
the acids. 

N 2 5 + H 2 == 2HN0 3 — Nitric acid - 
2S0 3 + 2H 2 = 2H 2 S0 4 — Sulphuric acid. 
P 2 5 + 3H 2 = 2H3PO4— Phosphoric acid. 

Comparing these three acids HN0 3 , H 2 S0 4 and 
H 3 P0 4 , we note that we have 1, 2 and 3 hydrogen 
atoms present respectively. One or all of these hydro- 
gen atoms may be replaced by a metal or electro- 
positive radical to form salts. These acids are there- 
fore termed respectively mono-, di- and tri-basic. 

110. Salts. — When all the hydrogen atom? are re- 
placed, as NaN0 3 , K 2 S0 4 and (NH 4 ) 3 P0 4 , we have 
a neutral salt, chemically speaking. The fact of 
the matter is, that the last named salt is actually alka- 
line to litmus paper, but it is neutral chemically, be- 
cause all the hydrogen has been replaced ; that is, it 
is no longer acid. If only a portion of the hydrogen 
be substituted, we have an acid salt ; that is, a 
salt with acid properties, for example, NaHS0 4 or 
CaHP0 4 . Calcium is bivalent, hence replaces two 
hydrogen atoms. It is obvious from the above, that 
hydrochloric or nitric acid can form only neutral salts, 
as from one of our first definitions an atom can not 
be divided. All the hydrogen need not necessarily be 



ORGANIC CHEMISTRY. 73 

replaced by the same metal, but the metals or radicals 
may be different, giving double salts, as (NH 4 ) 
MgP0 4 , ammonium magnesium phosphate, magne- 
sium being bivalent. 

EXPERIMENTS. 

I. Dissolve a little ordinary phosphorus in carbon disulphide in 
a test tube and pour the liquid upon a filter paper. Lay it on an 
iron stand to dry. 

II. Touch a small piece of phosphorus with a test tube filled 
with hot water. 

III. Place a small piece of phosphorus in a dry test tube, drop 
in a tiny crystal of iodine and warm. The re-action begins at 
once. A small amount of phosphorus iodide is volatilized and 
the rest is changed to the red variety. Cautiously add water, pour 
off, and test the solubility of the red phosphorus remaining in 
carbon disulphide. Does it take fire as easily as the other kind ? 

IV. Set fire to a small piece of phosphorus in a bottle with a hot 
wire. Close the bottle loosely, and after the reaction is over, insert 
a piece of moist, blue litmus paper into the bottle. 



LESSON XVIII. 

ORGANIC CHEMISTRY. 

111. Old Divisions. — Carbon combines with hydro- 
gen in different proportions to form thousands of com- 
pounds. The number is so very large that a certain 
division of chemistry treats alone of those compounds. 
It is called Organic Chemistry. Years ago chemistry 
was divided into three great divisions — chemistry of the 
mineral, animal, and vegetable worlds. It was held 



*74 SCHOOL CHEMISTRY. 

that distinct and separate laws governed each kingdom. 
Later, the barrier between the animal and vegetable 
chemistry was torn down, but it was still maintained 
that the laws of inorganic or dead nature could not 
hold for substances which were the products of vital 
force. In fact the religious fanatics, who ruled all in- 
tellectual life of the day, regarded it as sacrilegious to 
attempt the artificial production of substances ordinarily 
found only as the result of the action of life. 

112. Important Date. — In 1828 a great chemist, 
named Wohler, proved that an organic body (urea) 
could be produced in the laboratory from inanimate 
material. From that time on hundreds of chemists 
have worked in that field. For convenience the re- 
sults of their great labors are incorporated under one 
head, but the laws for Inorganic and Organic Chem- 
istry are the same. 

113. Vast Number of Organic Compounds. — 

Organic chemistry treats not only of the compounds of 
carbon and hydrogen, but of carbon and hydrogen with 
oxygen, sulphur, nitrogen, and phosphorus. All sub- 
stances used for illuminating our homes, except electric 
light of course, such as petroleum, gas, and oils, kero- 
sene, coal gas, and tallow candles, come under that 
head. It also treats of the composition of plant fiber, 
clothing materials, foods, animal juices, muscles, etc. 
Many medicines, as antipyrine, quinine, morphine; 
poisons, as strychnine and nicotine, are organic com- 
pounds. Stimulating substances, as alcohol ; seda- 



ORGANIC CHEMISTRY. 75 

tives, as chloral, ether, and chloroform ; fats, vaseline 
and wax, are included in that division. Many of 
these substances are very simple in their composition, 
and some are very complicated in structure. Their 
technical names usually accord with their chemical 
composition, as " pbenyl-dimethyl-pyrazolon " ; but 
frequently there is a simpler name, as " antipyrine," 
which is used in commerce, but gives no indication of 
its structure or composition. 

114. Some Properties of Organic Compounds. — 

All organic compounds may be burned with oxygen. 
In the decomposition the carbon burns to carbon diox- 
ide, hydrogen to water, and nitrogen to the oxides, or 
escaping free. Many of the compounds burn very 
easily ; some form violently explosive mixtures with 
oxygen. The flame resulting from the explosion is 
due to burning of a gas. Organic compounds, con- 
taining nitrogen when heated without oxygen, usually 
give off ammonia. 

115. Safety Lamp. — Iron is one of the best conduc- 
tors of heat, so a fine wire gauze conducts away the 
heat so rapidly that it does not permit inflammable gas 
on the other side to reach the kindling point. This 
principle, that flame will not pass through fine wire 
gauze, was made use of by Sir Humphrey Davy in his 
safety lamp. These lamps are now much used in coal 
mines, where explosions would occur as the result of 
the ignition of the combustible gases by the flame of 
an ordinary miner's lamp. 



76 SCHOOL CHEMISTRY. 

116. Luminosity. — Flame itself is colorless or pale 
blue, such as we see when an alcohol lamp is burning. 
.The luminosity of the flame, however, is due to the 
intense heating of very small particles of substance or 
incandescent gases. The ordinary white or yellow 
light of a gas burner, lamp, or candle is due to finely 
divided carbon heated to a white heat. A platinum 
wire held in the colorless flame glows and becomes lu- 
minous. Colored flames result when other substances 
are substituted for carbon. The green fireworks are 
due to barium ; yellow to sodium ; and crimson to 
strontium. 

117. Oxidizing and Reducing Flame. — The col- 
orless flame is hotter than the luminous flame. In the 
yellow flame the carbon is not burned all at once, but 
is, finally, in the brightest flame. If it were not a 
smoky flame would result. If we can so arrange, by 
the introduction of more oxygen, that the combustion 
of the carbon is at once complete, the flame becomes 
colorless and very much hotter. This may be accom- 
plished by a blowpipe. The blue flame, which 
shows an excess of oxygen, is called the oxidizing, 
while the yellow one, having more carbon than it can 
burn, is the reducing flame. The blowpipe promotes 
the burning and concentrates the heat at one point. 

EXPERIMENTS. 

I. Pour five drops of ether into a tin can. Cover it with a piece 
of paper. After ten minutes slip the paper just enough to leave a 
small opening. Standing at a distance apply a lighted taper to the 
opening. 



MARSH GAS. CHLOROFORM. ALCOHOL. 77 

II. Hold a piece of wire gauze over a gas burner. Turn the gas 
on and light it above the gauze. Now light the gas issuing from the 
burner, remove the gauze, and bring it down to the middle of the 
flame. 

III. Sprinkle some powdered charcoal in a colorless flame, or 
file a nail or other metallic substance above it. Hold a cold piece 
of clean porcelain in the yellow flame for a few seconds. 

IV. Prepare a glass tube by fusing a platinum wire into one end, 
as shown in Fig. 12. Drop a pinch of sodium chloride into a 



O 

Fig. 12. 

watch glass containing dilute hydrochloric acid. Moisten the wire 
with this solution, and hold in the colorless flame, which may be 
had by use of the plowpipe (Fig. 4, p. 34). Pour fresh acid 
into the watch crystal, and cleanse the wire by wetting with the 
acid and burning. Repeat until the flame is no longer colored. 
When the wire is clean repeat the experiment, using strontium 
and barium chlorides. 



LESSON XIX. 

MARSH GAS. CHLOROFORM. ALCOHOL. 

118. Marsh Gas. — Who has followed a squirrel 
through the woods into a swamp and not noticed the 
bubbles of colorless gas rise as you trod upon the de- 
caying leaves lying under water ? That very gas is 
a compound of carbon and hydrogen, called methane, 
or "marsh gas." It is produced in these swamps by 
the decay of leaves and other organic matter. It also 
occurs in large amounts in some coal mines, being 



78 SCHOOL CHEMISTRY. 

then termed " fire damp," because when mixed with 
the air and exposed to the flame it explodes with great 
violence. These explosions are very destructive to 
life and property. 

119. Substitution Compounds. — Methane (CH 4 ) 
has one carbon atom and four of hydrogen to its mole- 
cule. Applying the principle of valency, we may sub- 
stitute one chlorine atom for one hydrogen atom, as 
we remember both are univalent. In succession, chlo- 
rine may be caused to take the place of one, two, three, 
or even all four of the hydrogen atoms, giving com- 
pounds with the formulas, CH 4 , CH 3 C1, CH 2 C1 2 , 
CHClg, and CC1 4 . The only one we need speak of is 
CHCI3, called CHLOROFORM. 

120. Preparation of Chloroform. — As we regard 
chloroform as methane with three hydrogen atoms 
substituted by an equal number of chlorine atoms, it 
may result from the direct action of the sunlight upon 
a mixture of these two gases. Chloroform, a colorless 
volatile liquid, may be more easily prepared by dis- 
tilling dilute alcohol with chloride of lime. Chloro- 
form is used to dissolve many substances, but it is 
called for mainly as an anaesthetic in surgery. 

121. Organic Hydroxides. — Going back to me- 
thane, suppose one of the four hydrogen atoms to be 
substituted by the hydroxyl group, -O-H. The formula 
would be CH3OH, and the compound, an alcohol* 
This one is the so-called "wood alcohol." There is 
another hydrocarbon, a gas called ethane, very similar 



MARSH GAS. CHLOROFORM. ALCOHOL. 79 

to methane, which has the formula, C 2 H 6 . We may 
regard it as two molecules of methane, less two hydro- 
gen atoms, or methane in which one hydrogen atom 
has been substituted by CH 3 — i. e., CH 3 . CH 3 . 

122. Ethyl Alcohol. — Suppose -O-H be substituted 
for one hydrogen atom in this ethane. We have 
C 2 H 5 OH, or CH 3 CH 2 OH, the formula for the or- 
dinary alcohol. Another way of looking at the formula 
is to regard alcohol as water, in which one hydrogen 
atom has been replaced by the compound radical, 
C 2 H 5 , called ethyl, as : 

H-O-H CH 3 CH 2 -O-H. 

123. Fermentation. — Alcohol is ordinarily pre- 
pared by the fermentation of sugar or starch. Fer- 
mentation is generally regarded as the result of the 
action of living organisms, which possess the power of 
breaking up such substances as grape sugar, giving 
off carbon dioxide. The equation : 

Grape sugar. Alcohol. Carbon dioxide. 

C 6 H 12 6 = 2C 2 H 5 OH + 2C0 21 

expresses this decomposition. The ferment is added 
to a weak solution of molasses or sugar in water and 
the surface of the liquid exposed to the air, as the 
germs require oxygen for existence and growth. The 
organisms are most active at the temperature of a 
warm summer day. The alcohol produced is dissolved 
in the water present. As alcohol boils at 78° C, and 
water at 100° C, they may be partially separated by 
distillation, the alcohol vapor passing off first. Abso- 
lute alcohol contains no water. It is obtained from 



80 » SCHOOL CHEMISTRY. 

the ordinary alcohol, which is ninety-five per cent, 
alcohol, by treatment with quick lime, which is slaked 
by the water present, and redistilling the alcohol from 
the slaked lime formed. 

124. Properties. — Pure alcohol has a peculiar, 
pleasant odor, and burns with a non-luminous hot 
flame. It has a great attraction for water. Alcohol 
is the principal solvent for substances of organic origin. 
It is extensively used in the arts, as in the manufacture 
of varnishes, perfumes, and the tincture of drugs. 

125. Not a Food. — In the dilute form, for it can be 
mixed with water in all proportions, it acts upon the 
human system as an intoxicant ; when concentrated, 
or taken in large quantities, it is a poison. When 
alcohol is taken internally a sense of warmth *is ex- 
perienced, but in fact the temperature of the body is 
actually lowered from one-half to two degrees Fahren- 
heit. Many ignorantly suppose they can endure 
greater cold, or cold for a greater while, if they fortify 
themselves with alcohol. Such is a mistake, as proven 
by the experience of the members of various Arctic 
expeditions. Those who eschewed the use of brandy 
or whiskey withstood the intense cold better than 
those who had recourse to it. Alcohol is not a food in 
the sense we ordinarily think of such, and should not 
be so considered. 

126. Beverages. — The many beverages in use de- 
pend for their efficacy upon the amount of alcohol that 
is present. The milder forms of beer, some European 
beers, for example, contain from two to three per cent. 



MARSH GAS. CHLOROFORM. ALCOHOL. 81 

of alcohol. American beer has from six to eight. 
Beers, besides alcohol, contain as a rule some nourish- 
ment. Light wines, as claret, have eight per cent., and 
whiskey and brandy sometimes contain as much as 
sixty, or even seventy per cent, of alcohol. These 
drinks are nothing but solutions of alcohol of various 
strengths with small amounts of different kinds of es- 
sences obtained from the fruit or grain from which 
the liquor is made. The evil effect of these strong 
drinks is so well taught in physiology that it is almost 
needless to warn one against their use. Suffice it to 
say, that knowing that the snake will bite, one is a 
fool to put his hand upon it. Most all the ill health, 
and nine-tenths of the unhappiness of the world, is the 
direct result of the abuse of the use of alcoholic stimu- 
lants. Like many poisonous substances, alcohol, when 
properly used under the direction of a physician, is a 
good medicine. 

EXPERIMENTS. 

I. Burn a little alcohol in a porcelain dish. Note flame. Add 
to the alcohol in turn a solution of sodium, strontium and barium 
chlorides. Burn in dish, washing the dish well after each experi- 
ment and using fresh alcohol each time. 

II. Pour a little alcohol in the palm of the hand. How do you 
account for the sensation felt ? 

III. Half fill a test tube with water. Cautiously fill the tube to 
overflowing with alcohol. Avoid mixing the two liquids during 
the pouring, then place the thumb over the mouth of the tube. 
Mix well by shaking. Remove the thumb without spilling any of 
the liquid. What do you notice? Explain. 

IV. Place a little of the white of a fresh egg in test tubes. In 
one add 1 cc. alcohol ; in the other, 5 cc. whiskey. 

Note. — It has been learned recently that fermentation may 
occur without the presence of germs. 



82 SCHOOL CHEMISTRY. 

LESSON XX. 

ETHERS. ORGANIC ACIDS. ESTERS. 

127. Ethers. Class. — Suppose we subtract a mole- 
cule of water from two molecules of alcohol ; we have 

CH3CH2OH tt a __ ^-^3^-^2-^n 
CH 3 CH 2 OH " M2U "~ CH 3 CH 2 >U 

a body called an ether. Alcohol is regarded as an 
hydroxide of ethyl ; ether is an oxide of ethyl. Let 
us go back to water to make it clear. 

Water. Hydroxide. Oxide. 

H-O-H Na-O-H Na-O-Na 

Alcohol. Ether. 

CH 3 CH 2 -0-H CH 3 CH 2 -0-CH 3 CH 2 . 

Sulphuric acid has the power of tearing water away 
from certain substances, heno.e we may use that reagent 
for removing water from alcohol to produce ether. 

128. Properties. — Ether is a colorless, very light 
liquid, which boils ever so easily (at 34.9° C.) In 
fact, on a hot summer day, it exists as a gas ; hence it 
evaporates with great rapidity, producing cold. It is 
very inflammable, and possesses a peculiar odor and 
taste. It is an excellent solvent for resins, fats and 
many organic substances. It has great value and use 
as an anaesthetic. 

129. Organic Acids. — In the production of alcohol 
by the fermentation of sugar, it was necessary to cut 



ETHERS. ORGANIC ACIDS. ESTERS. 83 

short the operation before the ferment had done all the 
damage possible. If the reaction, resulting from the 
ferment, be allowed to continue, the alcohol will be 
further oxidized and changed to acetic acid. Suppose 
we imagine alcohol with two hydrogen atoms substi- 
tuted by one oxygen atom, we have, 

Alcohol. Acetic Acid. 

CH 8 C-0-H CH3C-O-H 

H 2 ^ 

130. Acetic Acid. — Acetic acid is an organic acid, 
soluble in water in all proportions. All organic acids 
have the group -CO. OH, called carboxyl, present in 
them. An impure form of acetic acid, containing 
about four per cent, of the acid, is vinegar. Acetic 
acid is prepared on the large scale in two ways — by 
the oxidation of alcohol and by the distillation of 
wood. Pure concentrated alcohol, when exposed to 
the air, does not undergo change. Poor wines con- 
taining small per cents, of alcohol, however, on expos- 
ure to the air, gradually become sour. This is called 

wine vinegar," and the oxidation of the alcohol is 
due to the action of the ferment called " mother-of- 
vinegar." As great quantities of vinegar and acetic 
acid are used annually, a " quick vinegar process " has 
been invented. It consists essentially of barrels filled 
with beech wood shavings, which are covered with the 

mother-of-vinegar." Dilute alcohol is allowed to 
trickle down through the shavings, the air passing in 
the opposite direction. The liquid which went in at 
the top as alcohol emerges at the bottom as vinegar. 



84 SCHOOL CHEMISTRY. 

131. Organic Salts. — Alcohols act like hydroxides, 
as they really are, and the organic acids behave as 
ordinary acids do ; therefore they may combine to form 
organic salts. Some of these organic salts, called 
esters, often wrongly called "ethers," are among the 
most important substances of which we make use in 
daily life. 

132. Saponification. — Fats, as lard, beef fat, and 
butter, for the most part consist of these esters. They 
are composed of glycerol, commonly termed glycerine, 
which is an alcohol, combined with the complicated 
acids, palmitic, stearic, and oleic. Fats may be decom- 
posed into glycerol and the acids, if boiled with dilute 
acids or alkalies ; the process is called saponification, 
the act of making soap, for such it is. 

133. Soaps. — The hydroxides of some metals, as 
potassium or sodium, combine with the organic acids 
just as they combine with what are known as the min- 
eral acids — hydrochloric, for example. By boiling fat 
with potash we obtain glycerol and a mixture of potas- 
sium palmitate, stearate, and oleate, or soft soap. If 
sodium be used instead of potassium, we have hard 
soap, which is less soluble in water than the former. 
Now, calcium palmitate and stearate are quite insoluble 
in water. Hard water, as we learned, contains cal- 
cium salts in solution, which immediately form a cal- 
cium palmitate or stearate as soon as the soap is placed 
in the water. Consequently, hard water does not at 
first form a lather with soap. Soap is easily and cheaply 



ETHERS. ORGANIC ACIDS. ESTERS. 85 

made at home by saving all the wood ashes in a barrel 
and then treating them with water. This leaching 
dissolves out the potassium carbonate, which, when 
boiled with refuse fat, otherwise to be thrown away, 
gives soft or kitchen soap. Expensive soaps are usually 
made of purer material, colored, perfumed, and moulded 
into cakes of convenient size. 

134. Butter. — Butter is a mixture of fats as pro- 
duced by the various milk-giving animals. In addition 
to the fats mentioned above, it usually contains buty- 
rates also. If the butyrates are acted upon by certain 
ferments causing partial decomposition, rancid butter 
is the result. Other ferments give the sweet odor to 
butter. Oleomargarine is an artificial mixture of 
fats (palmitates, stearates, and oleates), colored yellow 
as a rule, and is frequently substituted for butter. If 
these fats were pure originally, there could be no objec- 
tion to the use of oleomargarine as a substitute for but- 
ter, only it should be sold as such, and not as butter. 

EXPERIMENTS. 

I. Pour a little ether in the palm of the hand, noting volatility, 
cold, and odor. 

II. In a test tube place a little butter. Pour in some ether. 
Shake. After solution place the tube in hot water. Have no fire 
near in working with ether. Why ? 

III. Test a little vinegar with blue litmus paper. 

IV. Place in a test tube equal portions of alcohol and acetic 
acid. Add a little concentrated sulphuric acid. Boil and note 
odor. Add precipitated chalk until no further effervescence is no- 
ticed. This is done to neutralize the acid. Filter and taste. The 
esters constitute many of the soda-water flavors. 



86 SCHOOL CHEMISTRY. 

LESSON XXI. 

CARBOHYDRATES. 

135. Carbohydrates. — In the formula given for 
sugar, C 6 H 12 6 , we notice that the hydrogen and ox- 
ygen stand in the same ratio to each other as they do 
in water — that is, H 2 0, 6(H 2 0). A large number of 
compounds, which, besides carbon, contain hydrogen 
and oxygen in that relationship, are classified as car- 
bohydrates (hydrate meaning water). Some of these 
substances are sugar, starch, and cellulose. 

136. Great Variety of Sugars. — There are a great 
many kinds of sugars. We do not mean by that 
brown, granulated, cut-loaf, or maple sugar, but that 
some sugars are solid and crystallizable ; seme liquid 
and non-crystalline, as honey ; some are sweet, and 
many have no taste at all. It is hard for you to under- 
stand that there is a sugar which does not possess a 
sweet taste, but such exist. Further, anything that is 
sweet is not necessarily sugar. We cannot go into a 
discussion of the complicated structure of these sugars. 
Some have the formula given above, some have double 
that formula less one molecule of water, as (C x 2 H 2 2 1 x ), 
C 5 H 10 O 5 , and so on. 

137. Common Sugars. — We get a sugar from grape 
juice called grape sugar. If sugar cane is compressed 
and the liquid obtained evaporated in large pans, cane 



CARBOHYDRATES. 87 

Sugar (C 12 H 2 2 1X ) crystallizes out. The thick mo- 
lasses left is an impure solution of sugar in water. The 
treacle obtained from certain kinds of cane has a 
slightly bitter-sweet taste, due to small amounts of 
mineral salts present. This is commonly called sor- 
ghum. We may also obtain a sugar from sweet milk, 
entirely different from the others. It is called milk 
sugar or lactose. 

138. Acids from Sugars. — All of these sugars, 
under the proper conditions, may be made to undergo 
fermentation with the formation of corresponding acids. 
For instance, milk sugar can be converted into lactic 
acid ; in fact, this is the change which occurs in the 
souring of milk. The acid produced coagulates the 
casein, a constituent of milk, causing it to thicken, 
forming " bonny clabber." 

139. Starch. — Starch contains, apparently, one 
less molecule of water than sugar, C 6 H 10 O 5 . Starch 
is found everywhere in the vegetable kingdom in large 
quantity — particularly in all kinds of grain, as wheat, 
barley, etc.; in tubers, as the potato; in fruits, as 
chestnuts and acorns. In the United States starch is 
mainly manufactured from maize, and in Europe from 
potatoes. 

140. Properties. — Starch has a granular structure, 
not crystalline. In the usual condition it is not solu- 
ble in water, but on being heated to 60 °C with water, 
the starch cells burst and the contents go into partial 



88 SCHOOL CHEMISTRY. 

solution. On cooling it forms a translucent masg, 
called starch paste. To prevent starch paste from 
souring or undergoing fermentation, a little salycilic 
acid should be added. When dried, as by a hot iron, 
it presents a certain inflexibility, and is used to stiffen 
collars, cuffs, etc., in the laundry. On being moistened 
it loses its rigidity. 

141. Cellulose. — Cellulose forms, as it were, the 
groundwork of all vegetable tissues.* The coarse fiber 
of the sturdy oak contains it no less than the tender 
shoots of the delicate heliotrope. It is, of course, more 
or less altered in form in these different substances. 
Cotton, hemp, and flax are almost pure cellulose. 

142. Chemist's Power.— Cellulose is amorphous ; 
insoluble in all ordinary solvents. It dissolves, how- 
ever, in concentrated sulphuric acid, which, when 
diluted and boiled, produces dextrin and dextrose. 
The latter is one of the sugars. From an old shirt the 
chemist can make a sugar, then alcohol and ether or 
vinegar. 

143. Explosives. — Concentrated nitric acid in the 
presence of strong sulphuric acid acts upon cellulose 
to form a nitrate. This so-called nitro-compound is 
the very explosive gun-cotton. It is soluble in a mix- 
ture of alcohol and ether, producing collodion-solu- 
tion, which is used in medicine and photography. A 
mixture of gun-cotton and camphor is used under the 
name of celluloid. Celluloid is plastic at slightly 



CARBOHYDRATES. 89 

elevated temperatures, and can then be moulded into 
any desirable shape, hardening as it cools. It takes 
fire very easily. 

144. Paper, in its many forms, is for the most part 
cellulose, which may come from any source. Linen 
or cotton rags, wood or straw, aire cut or torn into frag- 
ments. Caustic alkali is frequently used for cleansing 
and to aid in the disintegration. The pulp suspended 
in water is spread out in thin layers and passed be- 
tween heated rollers to give it compact form and to 
dry it. The large sheets are cut into any desired 
shape. Paper is made white by bleaching, and the 
various tints are due to the different coloring matters 
used. 

With the carbohydrates are included a number of 
substances which occur in nature called gums ; for ex- 
ample, gum arabic or tragacanth. 

EXPERIMENTS. 

I. In one test tube make a solution of glucose in water. In 
another add a pinch of saccharine to water. Taste both. The 
former is a sugar, the latter is not, yet it is 284 times as sweet as 
ordinary sugar. 

II. Boil some starch in water in a test tube. Note what takes 
place ; add a small piece of iodine. Heat some ground wheat, flour, 
with water in a test tube, and test also with iodine. 

III. Dissolve some cotton in cold concentrated sulphuric acid. 
Dilute quickly by pouring into a large amount of water. 

IV. Pour a little collodion solution (obtained from drugstore) 
upon a glass plate. After the liquid has evaporated, set fire to the 
remaining film. 

V. Apply a lighted match to a small piece of celluloid. 



90 SCHOOL CHEMISTRY. 



LESSON XXII. 



ORGANIC BASES. OILS. GUMS. 

145. Urea. — The inert black carbon can be made 
to unite with lazy nitrogen to form an active and very 
poisonous compound, gaseous cyanogen, C 2 N 2 . Hy- 
drogen can also combine with these two to form an- 
other gas equally as poisonous. It is said that one- 
fifth of a breath of either of these gases is sufficient to 
produce death. The latter compound is hydrocyanic 
or prussic acid, (HCN). It forms salts called cyanides. 
HON can further unite with oxygen forming cyanic 
acid, HCNO. This acid forms salts called cyanates — 
for example, ammonium cyanate, (NH 4 ) CNO. This 
body is one of the most important organic substances 
known, for it was this substance, which when heated 
allowed a re-arrangement of its atoms so that a body 
named urea was produced. This body had never be- 
fore been made except through the intervention of life. 
Urea, the result of the decomposition of nitrogenous 
substances in the body, served to break away the bar- 
riers previously existing between Organic and Inor- 
ganic Chemistry. 

146. Organic Bases. — All the compounds contain- 
ing carbon, hydrogen, oxygen and nitrogen are not 
acids ; some are basic. Some of them are called alka- 
loids, because they resemble the alkalies in their 
chemical action. They are usually found in plant and 



ORGANIC BASES — OILS — GUMS. 91 

animal juices combined with acids to form salts. In opi- 
um, for example, there are seventeen of these alkaloids 
upon which the medicinal properties the drug pos- 
sesses depend. In small doses either as the plain 
tincture (laudanum), or the flavored camphorated tinct- 
ure (paregoric), opium is a sedative ; in larger ones it 
is a narcotic poison. Morphine (from Morpheus, the 
god of sleep) is the chief narcotic principle of opium, 
and is also used to produce sleep and to alleviate pain. 

147. -Some Alkaloids. — Quinine obtained from Pe- 
ruvian bark is used in fever and as a tonic. Nicotine 
forms from two to eight per cent, of the volatile princi- 
ple in tobacco. One drop of it will kill a dog. Strych- 
nine from the mix vomica is a deadly constituent of 
the poison used on arrows by the South American In- 
dians. In minute amounts it is an excellent tonic ; 
but in doses of any size tetanic spasms ending in death 
result. It is one of the most deadly of the alkaloids. 
It is said that five one-hundredths of a gram was 
known to kill a man. Strychnine possesses in the 
highest degree an almost unfailing property of all alka- 
loids, namely, bitterness of taste. One gram will im- 
part a bitter taste to four thousand liters of water. In 
medicine these alkaloids are always used as salts, as 
sulphates or hydrochlorides. 

148. Tea and Coffee. — There are two alkaloids 
which many of us take into our systems every day. 
Coffee and tea contain an alkaloid called caffeine or 
THEiNE, according to the source. Besides one per cent. 



92 SCHOOL CHEMISTRY. 

of caffeine, coffee contains about fourteen per cent, of 
oil and fat with an essential oil, which on roasting is 
volatilized, giving coffee the pleasant aroma. Tea con- 
tains twenty-odd per cent, of extractive matter with 
essential oils, and about fifteen per cent, of tannin. 

149. Tanning. — Besides the stimulating effect of a 
decoction of tea, it possesses a very astringent taste due 
to the tannin. This tannin is an organic acid found 
also in the leaf and bark of the oak and hemlock, and 
in nut galls. It is soluble in water and coagulates al- 
buminous substances, as gelatin. On this last property 
depends its value to us in our every day life. Skins 
of animals are treated with milk of lime and scraped 
to remove the hair and fatty substances and then ex- 
posed for variable lengths of time, the longer the bet- 
ter, in vats with water and ground hemlock and oak 
bark. The water dissolves out the tannic acid (as tan- 
nin), which passing into the pores of the skin com- 
bines with the albuminous substances to form an in- 
soluble compound, the basis of our leather. Leather 
is blackened by washing it on one side with a solution 
of copperas, ferrous sulphate. Tannic acid combines 
with iron to form a dark iron tannate — in fact, an ink. 

150. Essential Oils. — The essential oils we men- 
tioned above differ from the ordinary oils in not being 
saponiflable with an alkali ; they are not esters, but a 
large number of them are alike in composition pos- 
sessing the same formula, C 10 H 16 . They are allot 
vegetable origin, being present in the petals of flowers, 



ORGANIC BASES — OILS— GUMS. 93 

as in the violet ; in seed, as caraway ; in leaves, as 
mint ; or root, as sassafras. Oil of turpentine, " spirits 
of turpentine," is an important member of this class 
of bodies. It is much used in making varnishes and 
in medicine. Two of its hydrogen atoms seem to unite 
with one of oxygen when exposed to the air, and a resin 
is formed. Thus we note that the turpentine around 
the mouth of a bottle in which it is kept becomes 
sticky, then resinous. This is in fact oxidation. Tur- 
pentine is an excellent solvent for many substances. 
In using it to remove grease spots fresh turpentine 
should be used, else a worse spot, more difficult to re- 
move, will result from the resin present. The value of 
turpentine in paints is largely dependent upon this 
oxidation and formation of resin, hence painters call it 
a " dryer." 

151. Resins. — If this resinous substance, called 
rosin, be dissolved in an essential oil, we have a bal- 
sam. Pitch, which exudes from incisions in certain 
trees, as the pine, is a balsam. By distillation the tur- 
pentine is separated from the rosin, which constitutes 
about three-fourths of the pitch. Amber is fossil resin. 
These resins do not decay, but are excellent preserva- 
tives. The ancient Egyptians embalmed bodies with 
these materials, and the mummies found in the Pyra- 
mids to-day are thus preserved after a lapse of over two 
thousand years. 

152. Rubber. — India rubber or caoutchouc is a 
gum, which exudes from certain trees in South America. 



94 SCHOOL CHEMISTRY. 

Pure rubber is white, but the kind we usually see is 
darkened by smoke from the fires used to dry it, or by 
an admixture of some coloring matter. Vulcanized 
rubber is made by heating the rubber with a little sul- 
phur. When strongly heated with a large percentage 
of sulphur, it becomes hard, brittle and capable of re- 
ceiving a high polish, and is used for buttons, combs, 
knife handles, etc. 

EXPERIMENTS. 

I. To a crystal of strychnine the size of a pin head, in a watch 
glass, add a drop of dilute HC1, and dissolve in a liter of water. 
Taste. 

II. To a little dilute solution of gelatine in water, add some 
water solution of tannic acid. 

III. Mix together a solution of tannic acid or nut galls and cop- 
peras in water. Add gum to thicken, and make the fluid run smooth 
from the pen. 

IV. Expose a tablespoonful of turpentine to the air for day. 

V. Treat a cloth spotted with grease with fresh turpentine, 
wash this out with alcohol, and that in turn with water. 

VI. Heat a small piece of hard rubber upon a silver coin. 
Sulphur turns silver black. 



LESSON XXIII. 
LIGHT METALS. 



153. Historical. — To-day we must go back and 
pick up some seemingly lost threads. The ancients 
knew seven heavy lustrous bodies, which they called 
metals. They were gold, silver, copper, iron, tin, 
lead, and mercury. Since that time a number of sub- 



LIGHT METALS. 95 

stances more or less like those mentioned have been 
discovered and classed with the metals 

154. Characteristics. — By the term metal is ordi- 
narily meant a substance that is heavy, opaque, but 
possessing lustre and capable of being hammered into 
thin sheets and drawn into fine wire. Now, there are 
several metals that actually float upon water, and some 
are too brittle to be beaten into plates, so we see that 
the classification possesses more convenience than accu- 
racy. But metals are generally solid at the ordinary 
temperatures, and are good conductors of heat and 
electricity Mercury is a liquid, however. Many of 
them liberate the hydrogen in acids when brought into 
contact with them, salts resulting. Combining with 
oxygen, as a rule, the metals form basic oxides, but in 
rare cases acid oxides are formed — arsenic oxide, for 
example. 

155. Electrolysis. — We have learned that acidified 
water is decomposed when an electric current is passed 
through it. Some compounds of the metals are also 
decomposed by the electric current. As the metals 
always separate out at the negative side of the current, 
we say that they are electro-positive. This power of 
decomposition by electricity, called electrolysis, was 
made use of in the early part of this century by Davy, 
who discovered the two light metals, sodium and potas- 
sium, by this means. 

156. Light Metals. — Some metals, as sodium and 
potassium, have the power of decomposing water, lib- 



96 SCHOOL CHEMISTRY. 

erating hydrogen, as we have seen. When thrown 
upon water the reaction produces a great deal of heat, 
so much that if the metals, which melt and roll about 
upon the water are confined, the gas takes fire, the metal 
being changed to a hydroxide. It is not necessary to 
confine the potassium, which takes fire anyhow. The 
bright metals, on exposure to the air, rapidly tarnish, 
the oxides being formed. This tarnishing, is the same 
as the rusting of other metals. To avoid the "rust- 
ing," the metals must be kept covered with petroleum 
or kerosene oil. Care must be taken never to allow 
large pieces of sodium or potassium to come into con- 
tact with water. Neither of these metals should ever 
be handled with damp hands. 

157. Caustics. — The sodium hydroxide made by 
the action of the metal upon water is commonly called 
" caustic soda." It is more usually made by heating 
slaked lime with sodium carbonate and plenty of 
water. Caustic soda is a white solid of a very disa- 
greeable alkaline taste. It corrodes the skin, having 
a greasy feel when dissolved in water, and is classed 
among the corrosive poisons. It comes from the man- 
ufacturer in white lumps or sticks. It is largely used 
in making " hard " soaps, as is the " caustic potash," 
potassium hydroxide, in making "soft" soap. 

158. Flame Reactions. — We have learned that 
sodium burns with a bright yellow flame. Potassium, 
which is very similar to sodium, gives a bluish violet- 
colored flame. If a mixture of their salts — the chlo- 



MAGNESIUM — ALUMINUM— ZINC. 9? 

rides serve best — be burned, the color of the potassium 
is hidden by that of the sodium. When testing under 
such conditions, hold a dark blue glass between your 
eye and the flame. The blue glass cuts off the sodium 
light and you only see the potassium as a gray streak. 

159. Occurrence. — On account of the strong attrac- 
tion these metals possess for other substances, we do 
not find them occurring free in nature. As com- 
pounds, however, they are widespread. The presence 
of potassium in the soil is necessary for crops. 

EXPERIMENTS. 

I. Float a filter paper upon water, and drop a small piece of met- 
allic sodium upon it. 

II. Make a concentrated solution of sodium hydroxide in water. 
Dilute a portion largely ; try the " feel " and taste. Place a piece 
of cloth in the strong solution and heat. 

III. Expose to the air, on a dry surface, a piece of freshly cut 
sodium. 

IV. In a colorless flame hold a platinum wire moistened with a 
solution of sodium chloride, then potassium chloride, then a mix- 
ture of the two. ( See Fig. 12, p. 77. ) Look at the flames through a 
blue glass. Slap a book in front of the flame. 



LESSON XXIV. 

MAGNESIUM. ALUMINUM. ZINC. 

160. Flash Lights. — There are two other so-called 
light metals that deserve our attention — magnesium 
and aluminum. Magnesium is a silver white metal, 
which retains its brightness in dry air, but tarnishes if 
moisture be present. We usually see magnesium in 



98 SCHOOL CHEMISTRY. 

the form of ribbon, wire, or powder, When heated, 
it takes fire, burning with a brilliant light of high 
actinic power. The "flash light" used in taking 
photographs at nights is produced by the burning of 
magnesium powder. The magnesium light has been 
seen twenty-eight miles at sea. The white powder 
produced when magnesium burns is magnesia or mag- 
nesium oxide. 

161. Aluminum. — How many of you have seen 
pictures of flying machines? Very few flying ma- 
chines have been successful inventions because of the 
great weight of the material used in construction. 
The bluish-white, very light metal — aluminum — prom- 
ises to help the flying enthusiasts not a little. 

162. Source and Manufacture. — Aluminum in the 
form of compounds occurs everywhere. It is the main 
constituent of clay. The difficulty of obtaining it in 
metallic form has made it too expensive until rather 
recently. At one time it cost as much as forty dollars 
per kilogram ; now it may be had for one dollar or less. 
The materials used as a source for aluminum are 
bauxite, corundum and emery. They are either hy- 
droxides or oxides of aluminum. The purity is fre- 
quently dependent upon the locality from which they 
come. A very intense heat is necessary to cause carbon 
to rob these compounds of their oxygen. The diffi- 
culty of obtaining this high heat economically was 
the obstacle in the w r ay of reducing the cost of this 
metal. Large electric furnaces are now used in the 
electrolysis of a solution of alumina in fused cryolite, 



MAGNESIUM — ALUMINUM— ZINC. 99 

a mineral containing sodium and flourine, besides 
aluminum. The carbon combines with the oxygen, 
forming carbon dioxide, the molten aluminum being 
drawn off from the bottom of the large carbon-lined 
crucible. 

163. Properties. — Aluminum takes a high polish, 
and is very sonorous. It is half as heavy as iron, but 
not so strong. It is, however, tenacious, very mallea- 
ble and ductile. It is little altered on exposure to the 
air. It is soluble in hydrochloric acid and the alkalies 
— sodium and potassium hydroxides — hydrogen being 
evolved. Because it is so easily attacked, it does not 
serve well for cooking utensils. However, it is not 
poisonous, even when taken into the system. Large 
amounts would derange the digestion. 

164. Uses. — Aluminum has a wide range of useful- 
ness. It is used in making optical instruments and 
delicate balances, where lightness of material having 
only moderate strength is necessary. Aluminum 
bronze, which contains ninety per cent, of copper and 
ten of aluminum, is very hard and malleable, having 
the tenacity of steel. It is gold colored, and can be 
highly polished. Accoutrements for soldiers, who 
must march great distances, are being made out of 
aluminum. It can best be worked when heated a 
little above the boiling point of water. 

165. Zinc is a peculiar metal belonging to the same 
class as magnesium. It is grayish-white and crystal- 



100 SCHOOL CHEMISTRY. 

line in structure. At ordinary temperatures and at 
200° 0., zinc is very brittle, but at 140° C. it is quite 
malleable, and may be rolled into sheets. 

166. Galvanized Iron. — Zinc decomposes most 
acids with an evolution of hydrogen. Commercial 
zinc is scarcely ever pure, but contains small amounts 
of lead, iron, carbon, and traces of arsenic and anti- 
mony. Zinc is not much affected by air, either dry or 
moist ; therefore it is used to coat iron piping to prevent 
rust. Iron so coated is called "galvanized iron," and 
is made by placing the cleansed iron for a moment in 
a bath of molten zinc. Zinc salts are poisonous. 
Almost all natural waters contain some acid, hence 
galvanized iron should not be used to conduct such 
waters, if they are to be used for drinking purposes. 
Zinc readily precipitates most metals from solutions of 
their salts. In the case of lead, it produces the "lead 
tree." 

EXPERIMENTS. 

I. Ignite one end of a piece of magnesium wire held by tweezers. 

II. Place a mixture of three parts magnesium powder and one 
of potassium chlorate in a piece of paper and set fire to the paper. 
Do this in a dark room and avert the eyes. 

III. In three test tubes containing dilute hydrochloric acid, add 
separately small piece of magnesium, aluminum and zinc. Test 
the gases given off with a lighted taper. 

IV. In a test tube containing sodium hydroxide solution, add 
several pieces of aluminum, and heat. Test the gas given off 
with a lighted taper. 

V. Suspend a strip of zinc in a strong water solution of lead 
acetate (sugar of lead). 



MERCURY— TIN — LEAD. 101 

LESSON XXV. 

MERCURY. TIN. LEAD. 

167. Quicksilver. — Closely akin, chemically, to 
zinc is the only liquid metal we know, mercury, often 
called quicksilver. Mercury sometimes occurs alone 
in nature. It is a silvery lustrous, very heavy liquid. 
It also occurs combined with sulphur in the red min- 
eral cinnabar. Many of the compounds of the metals 
with the non-metals or electro-negative elements have 
entirely different colors from any of the uniting sub- 
stances. Tin is white ; one of the sulphides is yellow, 
another brown. Red copper combines with chlorine 
to form a green compound, and the gray lead unites 
with oxygen to make yellow and red compounds. 

168. Properties. — Mercury remains a liquid 
through a wide range of temperatures, boiling at 360 °C, 
freezing at — 40°C. It expands almost uniformly for 
equal additions of heat, therefore it is used extensively 
in making thermometers. 

169. Amalgams. — Mercury dissolves many of the 
metals producing amalgams. Mirrors are made by 
taking advantage of this solubility of metals in mer- 
cury. A thin sheet of tin is spread upon a perfectly 
level surface and mercury poured over it. A clean 
glass plate is then pressed down upon the mercury, the 
greatest care being exercised to prevent the presence of 
any air bubbles. Weights are added to press out the 
excess of mercury. The tin dissolved in mercury ad- 



102 SCHOOL CHEMISTRY. 

heres closely to the glass, giving the bright reflecting 
background to our mirrors. 

170. Crystallized Metal. — Speaking of tin calls 
to mind the value of that beautiful white lustrous 
metal. Tin obtained in sticks creaks or "cries" when 
bent. This is due to the grinding of the crystals upon 
one another, for tin is highly crystalline. Sheet tin, 
used so much for roofing purposes, is, in fact, sheet- 
iron which has been covered over with a thin film of 
tin in a somewhat similar manner- to that by which 
galvanized iron is made. 

171. Sheet Tin. — Tin withstands the action of the 
weather even better than zinc, and as it does not cor- 
rode, serves excellently for roofing purposes. Sheets 
of tin alone would be too expensive. Iron is cheap, 
but would soon rust away and be of no value. In or- 
dinary sheet tin, the strong cheap iron is made use of 
and the non-corroding covering of tin obtained as well. 
We must bear in mind that there must be no small 
cracks in the tin coating permitting the exposure of the 
iron to the weather, for if there were, the iron would 
corrode even faster, as galvanic action would set in. 
To avoid this corrosion, as invariably the tin is cracked 
some in the handling, tin roofing is painted with a 
mineral paint, which is not attacked. Thus the cracks 
are filled up and no corrosion can result. 

172. A Soft Metal. — Lead is a near relative of tin. 
Lead is soft, however, and corrodes in the air. Lead, 
which may be easily cut, at first exhibits a bright sur- 



MERCURY — TIN — LEAD. 1 03 

face ; it rapidly becomes dull, however. Lead melts 
very easily and can be cast into moulds of any shape. 
When warm, lead may be squeezed through round 
holes something like sausage coming from a sau- 
sage mill, except that an iron plug may be so arranged 
to make the tube hollow. This lead piping is made 
use of in plumbing on account of the ease with which 
it may be bent or unions made. 

173. Lead, a Poison. — Lead salts are poisonous and 
cumulative in effect. Water containing dissolved oxy- 
gen, when passed through lead pipes, causes them to cor- 
rode, forming the hydroxide, which is soluble in water. 
This kind of water, which has passed through lead 
pipes, when drunk continually, will prove poisonous. 
If the waters be carbonated, the insoluble carbonate of 
lead is produced, and this acts as a protective coating, 
preventing further corrosion. As a rule, the amount 
of lead piping used is so small that there is practically 
no danger attending the use of the water for drinking 
purposes. 

EXPERIMENTS. 

I. Place several drops of a mercuric chloride solution (corrosive 
sublimate) upon a silver coin and rub it. What do you notice ? 
Conclusion ? Repeat, substituting zinc for the silver. Zinc poles 
in electric batteries are thus amalgamated. 

II. Cut a piece of lead with a knife and notice the exposed sur- 
face at once and again the next day. 

III. Dissolve a No. 8 bird shot in dilute nitric acid. Pour the 
solution into a liter of water and pass hydrogen sulphide into the 
solution. This is the method of detecting lead in drinking water, 
only the water is usually concentrated to one-tenth of the original 
volume by boiling. 



104 SCHOOL CHEMISTRY. 

LESSON XXVI. 

COPPER. SILVER. GOLD. PLATINUM. 

174. Colored Metals. — All the metals we have 
studied so far are white. There are a few that are 
colored ; copper is red. " Silver threads among the 
gold " tells beautifully of the gray hairs of on-coming 
age. 

175. Red Metal. — That metal, copper, is one of 
great use in the arts and manufactures. Hammered 
into sheets it is used to sheathe wooden ships ; drawn 
into wire it serves to conduct electricity. Although 
the metal is red in color, many of its compounds are 
green or blue. The red color of copper serves as a 
danger signal, for its compounds are poisonous. The 
alloys of copper are very important, as we shall see. 

176. Occurrence. — Copper occurs free in a con- 
glomerate rock along the shores of Lake Superior. It 
also occurs elsewhere as an oxide and sulphide. In 
the latter state it is usually accompanied by some silver 
sulphide. The process for obtaining the pure metallic 
copper from its ores is quite complicated. 

177. Ores. — Metals in mineral form may be very 
widespread in their occurrence. When these minerals 
are found in sufficient quantity to be profitably worked, 
they are termed " ores." 



COPPER — SILVER — GOLD — PLATINUM. 105 

178. White Metal. — Silver is a beautiful brilliant 
white metal, softer than copper, but harder than gold. 
It is exceedingly malleable and ductile, and the best 
known conductor of heat and electricity, except gold. 
Copper stands next to silver in this conducting power. 
Silver is unaltered on exposure to the air, and resists 
the action of hydrochloric and sulphuric acids. Like 
copper, it dissolves readily in nitric acid. 

179. Uses. — Silver is much used for jewelry and 
plate because it retains it high polish. If pure silver 
were used for coins it would soon wear away on account 
of its softness. To give hardness, silver in coins is 
usually alloyed with ten per cent, of copper. Silver is 
not acted upon by the fused hydroxides of the alkali 
metals. On exposure to sulphuretted hydrogen it turns 
black. This black sulphide of silver goes under the 
incorrect name of " oxidized silver." 

180. Noble Metals. — Now there are some metals 
that are not acted upon by the acids when used singly. 
The so-called u noble metals," gold and platinum be- 
ing taken as examples, are soluble, however, in a mix- 
ture of concentrated hydrochloric and nitric acids. 
This mixture is called "aqua regia," because it dis- 
solves these royal metals. These metals are seldom 
found in nature combined with other elements. Al- 
though they come into contact with oxygen and sul- 
phur through long ages, as all lie together buried in the 
earth, they seem to disdain any intimate relationship. 
This is more especially so of platinum, as gold occurs 
in places as sulphide and telluride. 



106 SCHOOL CHEMISTRY. 

181. Malleability and Ductility. — Gold is a beau- 
tiful yellow metal. When in the finely divided state 
it appears ruby red. Much of the red colored ruby 
glass is due to gold in this state of subdivision. Gold 
is the most malleable and ductile of all the metals. It 
may be hammered into such thin sheets, that it re- 
quires one hundred thousand of them to make one 
centimeter. This gold leaf transmits green light. One 
gram of gold may be drawn into -four kilometers of 
wire. 

182. Measure of Fineness. — Gold is very soft, 
therefore it is alloyed with copper to harden it to pre- 
vent its wear in use. It is extensively used for coins, 
jewelry, gilding and other purposes. The purity of 
gold in jewelry is estimated by " carats." Pure gold 
is "twenty-four carats fine." Ordinary watches and 
rings are of fourteen or eighteen carat fine gold. 

183. Fusibility. — Platinum is a heavy, soft metal 
of tin white color. Gold melts at about 1100°C, and 
platinum at almost 2000 °C. Platinum is malleable 
and ductile and is not acted upon by most chemicals, 
hence it is hammered into different shapes for use in 
chemical laboratories. Such metals as lead when heated 
in platinum ware form a fusible alloy, producing a hole 
in the vessel. Platinum may be welded like iron at 
red heat. It possesses the property of absorbing large 
amounts of gases after being heated. This absorption 
of gas by a metal is called " occlusion." Under the 
influence of heat and cold platinum expands and con- 



ALLOYS. 107 

tracts almost equally with glass, therefore it is used to 
conduct electricity through glass in incandescent elec- 
tric lights. 

EXPERIMENTS. 

I. Dissolve (out of doors) a few copper scraps in concentrated 
nitric acid. Add to a portion of the solution ammonium hydrox- 
ide in excess. Note the color of both solutions. 

II. (a) Stick a bright nail in a solution of copper sulphate, 
(b) Add a few drops of sulphuric acid to the solution, and insert 
narrow strips of platinum and zinc, allowing the outer ends to 
touch. Electroplating. 

III. Expose a dime to the fumes of hydrogen sulphide. 

IV. Try to dissolve a small piece of platinum wire in HC1, 
HN0 3 and H 2 S 4 separately. Finally try a mixture of two parts 
of HC1 and one of HN0 3 , both concentrated. Save the solution. 

V. Heat a small piece of lead upon a platinum wire. 



LESSON XXVII. 
ALLOYS. 



184. Alloys. — In some of our previous lessons, we 
used the term alloy, without denning it. An alloy is 
a mixture or compound of several metals brought 
about by melting them together. Alloys assume new 
and different properties from those of the constituents, 
depending upon the proportions of the metals used. 
The alloys are frequently more useful than the pure 
metals themselves. Gold and silver are so soft that 
articles made of them would soon wear away in the 
necessary handling in commercial transactions with a 



108 School chemistry. 

consequent depreciation in value. These metals alloyed 
with ten per cent, of copper have been found to be suf- 
ficiently hard to withstand much loss in handling. 

185. Brass. — There are other" alloys of copper con- 
taining that metal in large amount. Doubtless, so far 
as usefulness is concerned, copper is more valuable 
than gold or silver, for it is the main constituent of 
brass, bronze and bell metal. Brass is composed of 
copper, two or three parts, and zinc one part. This 
alloy is extensively used for ornamental purposes, etc. 
The greater the proportion of copper, the more mal- 
leable and ductile is the alloy. One per cent, of lead 
is ordinarily added during the melting to make the 
alloy soft enough to be cut on a turning lathe and 
to prevent the metal from sticking in the teeth of 
files used in shaping the material. When a larger 
amount of lead is used the alloy assumes the same 
color as gold, and is used as spurious gold. It soon 
tarnishes on exposure, however. 

186. Bell Metal. — Bronze is an alloy of copper and 
tin. In one proportion for awhile it served to make 
cannon, and in another it still serves to make our 
church bells. An alloy to be used in making ordnance, 
must be tough to prevent explosion of the gun, elastic 
to yield slightly to the large volume of gases generated, 
and hard to avoid being worn away by the projectiles 
used. Usually, a little phosphorus is added before 
casting to make these properties more pronounced. 
Bell metal must, of course, be sonorous, and it is 



ALLOYS. 109 

always hard and brittle. Bronze is easily cast — that 
is, when melted, it will assume the shape of any mould 
into which it may be poured. For this reason many 
works of art are made of bronze. They do not suffer 
on exposure to the weather, but take on a beautiful 
rich rust, called patina. The peculiar lustre of the 
metal may be seen through this green coat. 

187. Casting. — Alloys containing zinc, on cooling 
from the molten state tend to shrink, therefore brass is 
not a good substance for casting shapes with fine lines 
and corners. If, however, it be desired to cast around 
something — for instance, an iron ball — brass is an ex- 
cellent material for that purpose. There is another 
metal, however, used in alloys which does not shrink, 
but even causes expansion upon cooling. It is an- 
timony. 

188. Type-Metal. — In ancient times, knowledge 
was preserved by verbal tradition from one generation 
to another. This method was in turn replaced, after 
the art of writing was introduced, by handwritings 
upon parchment. About the fourteenth century, 
wooden blocks with letters cut on them, were used for 
printing purposes. These, however, were too perisha- 
ble. And in the century following, metal was for the 
first time used to make types. Type-metal should be 
strong, able to withstand pressure, easily melted, so 
that it can be recast, as constant use wears it away. 
On comparing a capital "I" and a small "1," or an 
"e" and "c," we see how necessary it is to have a 
metal which, in casting, will flow out, or on cooling, 



110 SCHOOL CHEMISTRY. 

expand into the smallest depression in the mould that 
the true character of the type may be represented. 
Four parts of lead mixed with one part of antimony 
give us this type-metal, which is usually cast under 
pressure. 

189. Solder. — Alloys frequently melt at lower tem- 
peratures than the metals of which they are com- 
posed. Tin melts at about 230° C, and lead at 330° C, 
yet a mixture of equal parts of these metals melt at 
186° C. This is the "soft" solder used by tinners. 
" Hard " solder contains copper, zinc and tin. There 
are many kinds of solder composed of different metals 
according to the kind of union to be made. The sur- 
faces of the metals to be joined together by soldering 
must be bright and free from oxide, else the union will 
not be close. The air must be excluded during the ope- 
ration also, to prevent the formation of oxide under 
the influence of heat. This is usually done by rub- 
bing powdered borax or rosin over the clean surface 
before applying the heated soldering iron These sub- 
stances also dissolve the metallic oxides formed during 
the heating, and thus help to keep the surfaces to be 
soldered untarnished. A good " non-rusting " solder- 
ing fluid is made by dissolving zinc in hydrochloric 
acid and adding ammonium hydroxide until the ex- 
cess of acid is neutralized. (How may we recognize 
this neutral point ?) 

Instead of having experiments with this lesson, a 
printing office, preferably where electroplating is done, 
and a tin shop, could be visited with profit. 



IRON. Ill 



LESSON XXVIII. 

IRON. 

190. Base Metal. — Of what value would a king be, 
if he had no subjects ? It may be asked of what value 
would the noble metals be, if there were no base ones ? 
A nation is not rated according to the king, or presi- 
ident, but according to the people and their industrial 
value. We may consider just one more metal, the 
value of which is almost incalculable ; without which 
there would be no life. This common metal, iron, 
seems to have been placed on earth not only as a means 
for man's progress, but as a necessity for his very exis- 
tence. Very likely the doctor has prescribed an " iron 
tonic " for most of us. 

191. Occurrence. Impurities. — The occurrence of 
iron combined with other elements is universal, not 
only in the mineral world, but as well in all the realms 
of life, animal and vegetable. The iron ores, magne- 
tite (sometimes called lodestone), brown and red hema- 
tites and so forth, occur in vast quantities all the world 
over. The great and serious difficulty is to obtain the 
metal comparatively free from impurities. Ores of all 
kinds always occur surrounded by and mixed with 
other rock. The main constituent of rocks is silica, an 
oxide of silicon. Sulphur and phosphorus sometimes 
occur in iron ores to the extent of three per cent. 
Phosphorus has the peculiar effect upon iron of making 



112 SCHOOL CHEMISTRY. 

it brittle when cold, " cold short." Sulphur causes 
the iron to crumble when hammered or rolled hot, 
"hot short." It is easily seen that the presence of 
these substances is very deleterious to the usefulness 
of the metal, yet perfectly pure iron is a substance 
rarely seen. 

192. Manufacture. — To get iron in a metallic state 
the ore in lumps from the size of one's fist to the head 
is mixed with coke and limestone. The carbon of the 
coke combines with the oxygen of the ore forming 
carbon dioxide and leaving molten metallic iron. If 
limestone, calcium carbonate, be heated intensely with 
silica, they will combine, forming a glass, which is 
liquid at the high temperatures necessary to deoxide 
the iron ore. This glass is called " slag," and dissolves 
out a great deal- of the phosphorus and sulphur, and 
prevents the reduced iron from being reoxidized by the 
air pumped into the furnace near the bottom. This 
process of removing impurities is called "fluxing." 

193. Iron Furnace. — Very large quantities of iron 
are worked with ; hence huge furnaces, twenty-five 
meters high and six meters in diameter, are used. The 
ore, coke, and limestone are dumped into the top of 
the furnace in cart loads at a time. A high tempera- 
ture is necessary for the chemical changes to take place, 
and, as the quantities used are enormous, to get that 
temperature immense blowing engines are kept pump- 
ing air into the sides near the bottom of the furnace, 
like the bellows at a blacksmith's forge. The tempera- 



IRON. 113 

ture reaches as high as 1500°C, or higher, in the hot- 
test part of the furnace. The molten iron, being 
heavier than the slag, sinks to the bottom of the 
furnace and is drawn off and run out into trenches in 
sand. From time to time the slag, which occupies 
considerable space, is drawn off from holes higher up 
in the furnace. It is cooled by water being thrown 
upon it, which makes it porous. This is sometimes 
used for railroad ballast. If the amount of phosphorus 
is considerable, as it is in basic steel slag, it is used as 
a fertilizer. 

194. Cast Iron. — The iron, drawn from the bottom 
of the furnace, after cooling, may be either white or 
gray, and when broken presents a crystalline appear- 
ance. This is ordinary " cast iron," and contains from 
2 to 6 per cent, of carbon. The carbon has come from 
the coke used to reduce the iron oxides to the metallic 
state. In the white cast iron, the carbon is combined 
with the metal, causing it to fuse more easily than the 
gray. In dissolving white cast iron in an acid some 
of the hydrogen liberated combines with the carbon, 
forming disagreeably smelling hydrocarbons, easily 
detected in the gases given off. The gray cast iron 
has some of its carbon combined, but most of it is in 
the form of minute crystals of graphite. The more 
combined carbon there is present, the easier is the iron 
fused and worked. 

195. Steel and Wrought Iron. — This crude, im? 
pure form of iron requires further special treatment, 



114 SCHOOL CHEMISTRY. 

according to the use to which it is to be put ; for in- 
stance, by reducing the amount of carbon to from 0.2 
to 1.5 per cent, we obtain steel. When the percentage 
of carbon becomes even lower than 0.2 of one percent, 
we have wrought iron. Wrought iron is the least 
fusible of all the varieties. The blacksmith buries his 
bar of iron to be forged in a bed of hot coke, not only 
to heat it so that he may hammer it into shape, but 
also that it may absorb carbon to replace that burned 
out by previous work. The absorption of this carbon 
makes the iron melt more easily. 

196. Tempering. — All iron in bars is crystalline. 
Steel is only one of the varieties of iron possessing 
peculiar properties of its own. For instance, if we 
allow it to cool slowly after heating, it becomes quite 
tough, but comparatively soft. It may easily be dented 
with a hammer. If it be cooled very quickly, as by 
plunging into water when white or red hot, it becomes 
exceedingly hard, but brittle. This is called " tem- 



197. Importance. — When we stop to think that it 
takes several thousand dollars to put an iron furnace 
into operation, or " blowing in," as it is called, in addi- 
tion to the cost of construction, and then recall the 
immense number of such furnaces in the world, and 
the innumerable uses made of iron, from a small watch 
spring to huge engines, we stand in awe at the stupen- 
dous amount of capital necessary to manipulate this 
simple base metal, 



METALLIC OXIDES. 115 

EXPERIMENTS. 

I. Dissolve a little iron in a mixture of HC1 and HN0 3 . Evap- 
orate to dryness in a porcelain dish ; add a little more HN0 3 , and 
dry again, finally ignite. One of the oxides of iron is produced. 

II. Place some blood in a porcelain dish, add several drops of 
HN0 3 and evaporate to dryness, and heat until no more fumes 
come off. Old blood stains upon cloth are usually due to the iron 
present. 



LESSON XXIX. 
METALLIC OXIDES. 



198. Oxides of Metals. — All metallic elements 
form compounds with oxygen, hence there is a large 
number of oxides. Many of them exist free in nature, 
but many require the most careful laboratory manipu- 
lation for their preparation. 

199. Colors of Oxides.— Most of the iron ores are 
oxides. They differ in color. In fact, the metallic 
oxides are of almost all colors, from white to black. 
Mercuric oxide, from which Priestley obtained oxygen, 
is red. One of the oxides of lead is yellow, another 
red, and still another is brown. Manganese, too, has 
several oxides, the most prominent one being the black 
or dioxide, frequently called binoxide. 

200. Lime. — If marble — calcium carbonate, also 
called limestone- — be heated intensely, it gives off car- 
bon dioxide. The oxide of calcium, or our ordinary 
" quick lime/' remains. When quick lime is placed 



116 SCHOOL CHEMISTRY. 

in water it' " slacks." Sufficient heat is sometimes 
produced to cause the water to boil. This heat is the 
result of the chemical action brought about when the 
water unites with the calcium oxide to produce the 
hydroxide or "slaked lime," 

CaO+H 2 0=Ca(OH) 2 . 

If quick lime be exposed to the air for a long time, it 
absorbs moisture and carbon dioxide, forming the 
hydrate and carbonate : 



CaO-fCCL=CaCO 



In such a state, it no longer has value as a constituent 
of mortar. 

201. Paints. — The red oxide of iron, amorphous 
ferric oxide, Fe 2 3 , mixed with oil, is much used as a 
paint for metallic surfaces. This "mineral paint" is 
not affected by moisture or oxygen, hence forms an 
excellent protective coating against rust. By paints, 
we ordinarily mean substances that are, as a rule, 
insoluble in water, and are mixed with either a weak 
glue solution (being then termed water-colors), or with 
linseed oil (called oil-paints). These insoluble sub- 
stances may be colored or white with the addition of 
sufficient coloring matter to give the desired tint. 
Many of the coloring matters are soluble in water. 

202. White Paints. — The basis of most white 
paints is a compound of lead, called white lead. Sul- 
phuretted hydrogen forms with lead a black compound } 



METALLIC OXIDES. 117 

lead sulphide. Therefore, if this gas be in the atmos- 
phere, and it is desired that the paint retain its original 
brightness, something else than a lead compound must 
be used as the body of the paint. Zinc oxide, called 
"zinc white," is much used as a substitute, the sul- 
phide of zinc being white. It is much more expensive 
than white lead, and possesses less " covering " power — 
that is, more of the substance is required to cover the 
surface — but it gives a peculiar beautiful white gloss. 
White lead is sometimes adulterated (weighted) with 
the heavy barium sulphate. 

203. Gems. — The light metal, aluminum, is the 
most abundant element upon the earth's surface, ex- 
cept oxygen and silicon, and it has but one oxide. 
This oxide, alumina, A1 2 3 , is white when pure, but 
it occurs in nature as the gray corundum, and crystal- 
lized as the ruby and sapphire, which have their 
characteristic brilliant colors. Emery is an impure 
corundum. All these minerals are very hard, ranking 
next to the diamond, which is the hardest of all min- 
erals. On account of their color and scarcity, rubies 
and sapphires are very valuable, being classed as 
"gems." Emery and corundum, on account of their 
hardness, are used for grinding and polishing hard 
surfaces. 

204. Oxides for Illumination. — Some of the ox- 
ides not only rank amongst the hardest known mate- 
rials, but are the least affected by heat — only the most 
intense heat fusing them. To utilize this infusibility, 



118 SCHOOL CHEMISTRY. 

the Auer-Welsbach gas-burner was invented. A bag 
of cotton gauze is dipped into a solution of thorium 
and zirconium nitrates and allowed to dry. When 
strongly heated, the cotton cloth is burned away and 
the nitrates decomposed, and we have a white gauze 
made of the oxides of the metals which had been in 
solution. This infusible gauze, when ignited suffi- 
ciently, gives a pleasant, soft, white light. 

205. Calcium Light. — What is known as the " cal- 
cium light" is produced by directing the intensely hot 
oxyhydrogen blowpipe flame upon quick lime. The 
light is blinding in its brilliancy, and the lime is 
heated to over 2000° C. without melting. 

EXPERIMENTS. 

I. Drop a piece of quick lime the size of a walnut into half a 
liter of water. After all action has ceased, filter the solution into 
a porcelain dish and pass in carbon dioxide until the precipitate 
produced is partly redissolved. Boil off the excess of carbon 
dioxide and filter again; dry the solid, which is "precipitated 
chalk." This is not our ordinary crayon chalk, which is calcium 
sulphate ; nor tailor's or French chalk, which is talc. 

II. Pass H 2 S over some white lead paint; zinc white paint. 

III. Place several lumps of marble in a hot bed of coals or in 
an open fire, and allow them to stay there for two hours. Remove 
with tongs, allow to cool, and place in a wide-mouth bottle with a 
cork. What is thus prepared ? Test its action on moistened blue 
litmus paper. 

IV. Direct the flame of a blowpipe cautiously, but continuously, 
upon a small pencil cut out of quick lime. 



CHLORIDES. 119 

LESSON XXX. 

CHLORIDES. 

206. Salts. — One of the simplest salts is common 
" salt." This condiment, actual food, is sodium chlo- 
ride. It must not be understood from this that all 
salts possess a salty taste. 

207. Salt Beds. — Sodium chloride occurs in small 
amounts all the world over. In some places, however, 
as a mineral, it occurs in large beds, usually in sedi- 
mentary geologic formations. Such beds have been 
discovered in Germany, England, at Petit Anse, Lou- 
isiana, Saltville, Va., Syracuse, N. Y., etc. It also 
occurs in salt springs. These saline springs are the 
result of the solution of this crystalline mineral in un- 
derground water. In some places the water from such 
springs has accumulated, and as the liquid has been 
removed by evaporation, the solid has remained be- 
hind. Thus were our salt lakes in Utah produced. 
The salt lakes are so strong in sodium chloride that it 
crystallizes upon the bodies of persons bathing in them. 
No fish exist in these lakes. Again, these saline 
springs have poured their waters into numerous flow- 
ing streams, and the salt has collected in the great 
oceanic reservoirs. The dry air, as a sponge, has soaked 
up the water vapor from the oceans. The rivers have 
continued to carry salt to the sea, in infinitely small 
amounts at a time to be sure, so that the amount of 
salt has gradually increased until it now reaches from 



120 SCHOOL CHEMISTRY. 

two to four and one-half per cent. The solid constitu- 
ents of the sea water are practically the same in all 
parts of the world, sodium chloride predominating. 

208. Salt Gardens.^Salt for a long time was ob- 
tained from the sea by an arrangement of " salines" 
or salt gardens, as it were. On a level shore in a hot 
climate a large reservoir was constructed. The water 
from the sea was allowed to run in through connect- 
ing canals. The heat of the sun evaporated most of 
the water, leaving a strong brine into which more sea 
water was run and allowed to evaporate. In this way 
a concentrated solution of the salts was secured. The 
sodium chloride being the least soluble of the salts 
present, separated out in crystals and was raked up on 
the ridges between the reservoirs. These crystals were 
not pure, but contained admixtures of magnesium and 
potassium chlorides. These latter absorbed water on 
exposure to moist air, and becoming liquid, sank into 
the ground underneath. The piles of salt were cov- 
ered with straw to prevent washing away by rain. 

209. Working Salt Springs. — Salt is frequently 
got by evaporation of the water from salt springs. The 
more extended the surface exposure the more rapid is 
the evaporation of the water which holds the salt in 
solution. To obtain this large surface, racks about ten 
meters high are built, and the space intervening be- 
tween the top and the ground is filled in with branches 
of trees. The spring water trickles down from the top, 
and the salt appears in sparkling crystals on each twig 



CHLORIDES. 121 

and is easily collected in baskets. Where salt occurs 
in large beds, it is mined as if it were an ore, or by 
dissolving the salt in water, which leaves the insoluble 
impurities, and evaporating the brine thus obtained. 

210. Impurities. — Sodium chloride crystallizes in 
cubes, sometimes separating in a hat-like form. The 
varieties seen in trade depend upon the size of these 
crystals, differing according to the rapidity of the crys- 
tallization. Fine table salt is crushed to the powdery 
state in which we usually see it. Pure salt is not deli- 
quescent, but most salt contains some little potassium 
chloride, which does absorb water, causing the salt to 
cake, as is frequently noted in salt cellars used upon 
the table. Usually salt contains from three to five per 
cent, of water, not as a constituent, but so bound up in 
the crystals as not to give evidence of its presence un- 
less the salt be heated. On the application of heat the 
crystals burst with a crackling sound, and are thrown 
about with some violence. This is called decrepita- 
tion. Decrepitation is due solely to the escape of 
water changed into vapor or steam by the heat. 

211. Uses. — Sodium chloride has a number of uses, 
being a necessary condiment in food. It is essential 
for the well being not only of man, but beast. A man 
weighing seventy-five kilograms contains in his body 
one-half kilo of sodium chloride. In order to main- 
tain this amount, as so much is got rid of daily, he must 
eat as much as seven and a half kilos of salt every 
year. All of us know the necessity for " salting" cat- 



122 SCHOOL CHEMISTRY. 

tie. A great deal of salt is used in making soda, chlo- 
rine, in tanning and in glazing certain rough brown 
kinds of earthenware. It is also much used as a pre- 
servative of wood, as well as meat, butter, etc. In fact, 
England produces over two million and the United 
States about one million tons per annum. 

212. Horn Silver. — Silver chloride, a white curdy 
substance, is of great interest, as it is so much used in 
photography. It is very sensitive to light, changing 
under its influence into a body, which is not soluble in 
the various mixtures called fixers, which do dissolve 
the unchanged chloride. 

EXPERIMENTS. 

I. Dissolve as much sodium chloride as possible in 200 cc. of 
boiling water; evaporate off three- fourths of the water by heating. 
Cover, cool slowly, and note the form of the crystals. 

II. Direct the name of a blowpipe upon some dry salt on a piece 
of charcoal. 

III. To a solution of silver nitrate in a test tube add several 
drops of HC1. Allow to stand in sunlight, and note the change on 
such exposure. 

IV. Photography. — Float a piece of sized paper upon a solution 
of sodium chloride. Dry and then float it for three minutes on a 
silver nitrate solution in a dark room. Press a fern leaf upon a 
glass and place the dried paper upon the leaf, and cover that with 
a board the size of the glass. Clamp all together with clothes 
pins, and expose the glass side to the direct sunlight. When suffi- 
ciently dark, remove the clamps and place the sheet of paper in a 
strong solution of sodium hyposulphite (ten per cent.), and wash 
thoroughly with water. The " hypo " solution dissolves the un- 
changed chloride, which has been protected from the light by the 
leaf. 

V. Deliquescence. — Expose some dry sodium chloride, potas- 
sium chloride and calcium chloride for a day or two. Which are 
deliquescent substances ? 



NITRATES — EXPLOSIVES. 123 



LESSON XXXI. 

NITRATES. EXPLOSIVES. 

213. Saltpetre. — The salts of nitric acid are called 
nitrates. Potassium nitrate does not occur in large 
quantities in any one place except in India, and then in 
only fair amounts. In small amounts, it is present in 
almost every soil. As enormous quantities of this so- 
called "nitre" or "saltpetre" are used every year, 
some artificial mode of production has had to be re- 
sorted to. Nature has been imitated as closely as pos- 
sible. It has been known for a long time that where 
organic matter containing nitrogen was decomposing 
in the presence of potassium carbonate, the nitrate 
always resulted. 

214. Nitre Plantations. Purification by Crys- 
tallization. — Wood ashes contain a high percentage 
of potassium carbonate. " Nitre plantations " are made 
by mixing these ashes and lime with manure and all 
kinds of refuse animal matter piled in layers, made 
porous by straw. These heaps are kept moist and ex- 
posed to the action of the oxygen of the air for two or 
three years. The nitrogenous matter is decomposed to 
nitric acid, which, having combined with the lime, is 
in turn decomposed by the potassium carbonate. The 
potassium nitrate thus obtained is secured by leaching 
the beds with water. As all nitrates are soluble in 
water, they are thus collected in solution, which, on 



124 SCHOOL CHEMISTRY. 

evaporation to a small bulk and cooling, allows the 
nitre to separate out in large crystals. One hundred 
parts of boiling water will dissolve two hundred and 
forty-four of nitre, whereas only thirteen parts are dis- 
solved if the water be at zero. Taking advantage of 
this, we can purify the nitre by repeated crystalliza- 
tions, a small portion of the salt being lost at each 
crystallization ; the impurities remaining in solution 
are washed away. 

215. Chili Saltpetre. — Sodium nitrate is called 
" Chili saltpetre," because enormous beds of it are 
found in that country. Sodium nitrate is much used 
as a fertilizer, as we shall see ; it is also used for the 
manufacture of potassium nitrate, which has more 
commercial value. 

216. Gunpowder. — Nitric acid and the nitrates 
have a large amount of oxygen present in them, there- 
fore one would imagine that substances mixed with 
them should burn more vigorously than otherwise. 
This fact is made use of in the manufacture of gun- 
powder. If we heat a piece of potassium nitrate upon 
charcoal, we note a very rapid burning of the carbon. 
The principal upon which gunpowder is used, is based 
upon the fact that a large volume of gas confined to a 
very small space exerts intense pressure or force. The 
more gas generated for the amount of material, the 
greater the explosive force. 



Nitrates— explosives. 125 

217. Products of Explosion. — The average gun- 
powder consists of a mixture of seventy-five per cent, 
potassium nitrate, twelve per cent, sulphur, and thir- 
teen per cent, carbon. This seems to be the best pro- 
portion of the three materials to produce the most 
rapid burning in order to convert the whole substance 
as quickly as possible into gaseous products. In this 
case, carbon dioxide and nitrogen are the principal 
gaseous products, and a small quantity of potassium 
sulphide is the main solid product formed. As we 
learn from our physics that the higher the tempera- 
ture the greater is the volume of the gas, therefore it 
is desirable to have the gas heated as much as practi- 
cable. We must '' keep the powder dry," else it will 
not burn, or at least burn slowly, thereby decreasing 
its effectiveness. Sodium nitrate attracts moisture, 
hence its use in gunpowder is undesirable ; it does very 
well in blasting powder, where cheapness is a great 
factor. Potassium nitrate is universally used for gun- 
powder. The noise of the explosion is caused by the 
confinement and sudden release of the gases, driving 
the air away, which, on its return, produces the report. 

218. History. — The amount of powder used every 
year is enormous. One of the largest cannon in the 
forts or on board of one of the tremendous war ships, 
requires nearly five hundred kilograms for each dis- 
charge. The early history of gunpowder is very ob- 
scure. Its first use in war was in the fourteenth 
century. 



126 SCHOOL CHEMISTRY. 

219. Nitroglycerine. — There are a great many ex- 
plosives, all dependent upon the principles stated above. 
They are also dependent upon the use of nitric acid in 
their manufacture. If we treat glycerol (glycerine) 
with a cold mixture of concentrated sulphuric and 
nitric acids, we get an oily substance incorrectly called 
nitro-glycerine — better, glyceryl nitrate. It is ex- 
tremely explosive, and when absorbed in saw dust or 
kieselguhr, chalky earth, it is sold as dynamite. 

220. Lunar Caustic. — The white crystalline silver 
nitrate, called "lunar caustic," has use in medicine as 
a cautery to destroy diseased flesh. 

EXPERIMENTS. 

I. Direct a blowpipe flame upon a piece of potassium nitrate on 
a piece of charcoal. Deflagration. 

II. Place a small amount of black powder on a piece of tin and 
set fire to it by means of a match attached to a long stick. Repeat, 
using moistened powder. 

III. Make a mixture of one part shellac, four parts strontium 
nitrate, and one-fifth part potassium chlorate. Make another, 
substituting barium nitrate for strontium. Set fire to small amounts 
of each. The colors can best be seen at night. 



LESSON XXXII. 
CARBONATES. 



221. Acid Salts. — We learned that when hydro- 
chloric acid was passed into a solution of sodium 
hydroxide the one hydrogen atom in the acid was re- 
placed by sodium. If carbon dioxide be passed into 



CARBONATES. 127 

water the hypothetical carbonic acid, H 2 C0 3 , is pro- 
duced. We do not really know the acid, but we do 
know, that if we pass carbon dioxide into a solution 
of sodium hydroxide we can obtain two salts. In one 
of these the sodium takes the place of only one hydro- 
gen atom and in the other both a*re replaced. This 
carbonic acid is, therefore, like sulphuric acid, in that 
it can form an acid and a neutral salt. 

222. Cooking Soda. — If carbon dioxide be passed 
through a strong solution, ten per cent, of sodium hy- 
droxide, we obtain at first the neutral salt, Na 2 C0 3 . 
If we continue to pass the carbon dioxide through the 
solution, very soon we notice white crystals separating 
out. This is the acid carbonate, according to the equa- 
tion, 

Na 2 C0 3 +H 2 C0 3 =2NaHC0 3 . 

This is our common cooking soda, and is used in 
making Seidlitz powders. Cooking soda, an ingredi- 
ent of the many artificial yeasts or baking powders, is 
used with sour (acid) milk to make bread " light." 

223. Chemical Action Promoted by Solution. — 

The acid carbonate contains a large excess of carbon 
dioxide, which is liberated when an acid is brought 
into contact with it in the presence of water. The 
powder in the white paper of Seidlitz powders is acid 
potassium tartrate, and the blue paper has acid sodium 
carbonate mixed with Rochelle's salts, according to the 
dose. If these two powders be mixed in the dry state, 



128 SCHOOL CHEMISTRY. 

we have no evidence of chemical action at all ; but if 
we add a little water effervescence is noticed at once. 
As chemical action is between molecules and atoms in 
the molecules, to promote chemical action they must 
be brought as close together as possible. When a sub- 
stance is brought into solution it is resolved at least 
into the molecular state, hence the molecules come 
closer together and chemical action takes place more 
readily. In the case mentioned the gas, carbon di- 
oxide, is produced with the solid, sodium potassium 
tartrate, a double salt, which remains in solution. 
The gas has an exhilarating effect upon the system, 
and the tartrate possesses its own peculiar medicinal 
value. 

224. Soda. — The manufacture of the neutral or sat- 
urated sodium carbonate constitutes one of the most 
important branches of chemical industry. Immense 
quantities, thousands of tons, are used every year in the 
manufacture of glass and soap, as well as in making the 
numerous sodium compounds. It is commonly called 
"washing soda". As sodium chloride is abundant and 
cheap, it serves as the starting point in the production 
of sodium carbonate. There are two great rival pro- 
cesses which have contended for the supremacy in the 
production of this material. 

225. Leblanc Process. — The Leblanc process de- 
pends upon the formation of sodium sulphate by the 
action of sulphuric acid on sodium chloride. The sul- 
phate is mixed with two parts of carbon and one 



CARBONATES. 120 

of limestone, and the mixture heated in a special fur- 
nace. The sodium carbonate produced is leached out 
with water from the impure material, and the solution 
concentrated by boiling. The carbonate combined with 
ten molecules of water separates out on cooling in large 
crystals. This exhibits further the great value the 
process of purification by crystallization possesses in 
aggregating like molecules and leaving the impurities 
in solution. 

226. Solvay Process. — The other method, known 
as the Solvay or ammonia-soda process, also makes use 
of a strong brine. The salt solution after being satu- 
rated with ammonia gas is placed in iron cylinders 
in which carbon dioxide is forced with a pump. The 
cylinders are kept cool by a water jacket on the out- 
side. Sodium hydrogen carbonate and ammonium 
chloride are the result of the chemical action which 
takes place. The former of these two compounds is 
rather insoluble, while the latter is very soluble and 
may be easily washed away. On heating the acid car- 
bonate changes to the neutral carbonate, C0 2 and H 2 
being driven off 

2NaHC0 3 =Na 2 C0 3 + H 2 + C0 2 . 

A new electrolytic process, the Castner-Kellner, pro- 
mises to displace both of these. 

227. Other Carbonates. — Potassium carbonate is 
made by evaporating the lye obtained from wood ashes. 
As the evaporating was formerly done in pots, it as- 



130 School chemistry. 

sumed the name of '• potash." Ammonium carbonate 
is the ordinary " smelling salts." 

228. Stalactites.— Calcium carbonate is insoluble 
in water, but easily soluble in acids, even carbon diox- 
ide and water (i. e., carbonic acid). Calcium carbonate 
is held in solution by waters carrying an extra amount 
of carbon dioxide. When that gas is evolved, the car- 
bonate separates out usually in a crystalline state. 
This is seen in many caves where the stalactite and 
stalagmite formations present such beautiful outlines. 
Temporary hardness of water is due to the presence of 
calcium carbonate held in solution by the carbon di- 
oxide present. As soon as the carbon dioxide is got 
rid of the carbonate separates out. This is accom- 
plished by boiling, the heat liberating the gas. The 
shells of snails, mollusks, etc., are composed mainly of 
calcium carbonate. 

229. Basic Salt. — As an example of a basic carbon- 
ate, we may mention white lead. Lead hydroxide is 
somewhat soluble in water, as noted, but it has a good 
covering power. Crystalline lead carbonate is trans- 
parent, but is insoluble in water. White lead is a com- 
pound of these two, in which the good qualities of each 
are utilized — that is, white lead is a basic carbonate, 
used as the ground work for most paints. 

EXPERIMENTS. 

I. Pass a steady stream of C0 2 into a ten per cent, solution of 
sodium hydroxide until a white precipitate begins to form. 

II. Mix intimately equal parts of powdered dry cooking soda 



SULPHATES— PHOSPHATES. 131 

and acid potassium tartrate (i. e., cream of tartar). Add water to 
the mixture. 

III. Leach some wood ashes with water and evaporate the solu- 
tion to dryness. To a portion add HC1. Test this solution with a 
platinum wire held in a colorless flame. Allow the other portion 
to stand until the next recitation. " Pearlash," i.e., potassium car- 
bonate, absorbs water. 

IV. To some powdered snail or oyster shells add HC1. Test the 
gas given off. 



LESSON XXXIII. 

SULPHATES. PHOSPHATES. 

230. Acid and Neutral Salts.— With sulphuric 
acid, we may have the acid and neutral salts. Sodium 
replaces one or both of the hydrogen atoms, giving, in 
the latter case, " Glauber's salts" (Na 2 S0 4 ), named 
after the chemist who discovered the substance. Much 
of this salt is produced in the Leblanc soda process. 
It possesses valuable use as a medicine. 

231. Epsom Salts. — Now, just as we have a di-basic 
acid, so may we have a di-acid base or metal which 
replaces two hydrogen atoms instead of one. Magne- 
sium is such a metal, as is calcium also. Magnesium 
sulphate (MgS0 4 ), " Epsom salts," so. named on ac- 
count of its abundant occurrence in a spring by that 
name, is much used in medicine. 

232. Gypsum. — Calcium sulphate occurs in large 
quantities as the crystalline mineral gypsum. A 



132 SCHOOL CHEMISTRY. 

mountain range in Switzerland is made up almost en- 
tirely of it. The other sulphates we have just men- 
tioned are very soluble in water, whereas calcium 
sulphate requires five hundred parts of water for solu- 
tion. As a rule, substances soluble in water are more 
soluble when the water is hot than when it is cold. In 
the case of calcium salts, the reverse of this is true. 
Calcium and magnesium sulphates, or chlorides, when 
dissolved in water, produce permanent hardness, as 
that property of such water is not lost by heating. 

233. Plaster of Paris. — Calcium sulphate, when 
mixed with water, forms a paste, which, after a portion 
of the water has evaporated, " sets" or hardens. It is 
called "plaster of Paris," and is calcium sulphate 
combined with two molecules of water. By gentle 
heat this water may be driven off and the sulphate 
will harden again when mixed with water ; for, in 
fact, this so-called plaster of Paris is the anhydrous 
sulphate obtained by heating gypsum (CaS0 4 +2H 2 0), 
which drives out the water of crystallization. If it 
be too strongly heated, however, it loses the power of 
forming a compound with water. Plaster of Paris is 
largely used in making casts and in surgery. One 
anhydrous form of calcium sulphate, called alabaster, 
is almost transparent, and is often used for carving 
beautiful statuary. 

234. Colored Sulphates. — Copper sulphate is "blue 
stone," so much used in telegraph batteries. Ferrous, 
or iron sulphate, is a green colored substance, com- 



SULPHATES — PHOSPHATES. 133 

monly called " copperas," although there is not a trace 
of copper in it. It is used as a deodorant. 

235. Tri-Acid Bases. — Aluminum is a metal that 
can replace three hydrogen atoms ; and, as there are 
only two in sulphuric acid, we see that one atom will 
require one and a half molecules of acid. Since we 
cannot have fractions of a molecule existing alone, we 
must have two atoms of aluminum and three mole- 
cules of sulphuric acid to produce the salt aluminum 
sulphate, A1 2 (S0 4 ) 3 . 

236. Alums. — Aluminum sulphate can combine 
with the sulphates of the alkalies — potassium, sodium, 
ammonium, etc. — to form double sulphates, an impor- 
tant class of bodies called alums. The aluminum can 
be substituted by iron or chromium in such com- 
pounds, the iron or chrome alums resulting. The 
common alum (aluminum potassium sulphate), with 
about an equal amount of water, is much used in 
medicine and adulterating baking powders. These 
beautifully crystalline compounds are much used in 
dyeing — not so much as dyes themselves, but as fixers 
of the colors. Many colors do not affect the cloth to 
be dyed, and require to be fixed or bound to it. Such 
dves are "adjective colors." The alums possess the 
property of fixing these colors, and are termed mordants 
or biters, as they are said to bite the color into the 
fabric. 

237. Phosphates. Universal Distribution. — Na- 
ture provides for all those dependent upon her. Being 



134 SCHOOL CHEMISTRY. 

essential for all forms of life, the phosphates are dis- 
tributed in small but generous amounts in the different 
kinds of soil. Plants require them for growth, and 
thirty per cent, of all bones is calcium phosphate. 
When unhindered, all thing are ordered for the perfect 
growth of each member of Nature's kingdom. Thus 
we find the grandest trees and the graceful deer in the 
uninhabited forests. But where man steps in and dis- 
arranges Her plans, he must then, by his own efforts, 
make good any drain he has caused upon Her goodly 
store. Nature had fully provided for those trees and 
deer. Let man clear away the forest and plant the 
field. By the removal of the wood, he has carried 
away much that, in decaying, would have been val- 
uable for other trees in their turn. Now he plants the 
field, harvests the crop, bearing away year after year 
great quantities of plant food. Soon " poor land " re- 
sults, as Nature cannot forever, unaided, supply the 
demand. 

238. Phosphate Mines. — Phosphoric acid is one of 
those valuable foods removed every year. Man has 
learned that he must replace every kilogram of phos- 
phoric acid he removes if he wishes to continue to 
derive profit from tilling the soil. Many years ago, 
long before the time our histories tell us of, the bones 
and teeth of many animals were thrown together and 
buried by the action of the water and other geologic 
agencies. At this time these deposits are very val- 
uable to us, as those bones and teeth are mainly com- 
posed of neutral calcium phosphate. This form of 



SILICATES — NATURAL AND ARTIFICIAL. 135 

phosphate is insoluble in water, and less directly 
available for plant food than it would be if it were 
soluble. The phosphate rock is therefore mined, 
crushed and treated with concentrated sulphuric acid. 
This treatment causes the formation of the hydrogen 
calcium phosphates, one of which is soluble in water. 
This is called "acid-phosphate," and is an important 
constituent in all fertilizers. 

EXPERIMENTS. 

I. Paste a narrow strip of paper, 5 mm. wide, around the edge 
of a coin. Spread with a camel's hair brush a milky solution of 
calcium sulphate over the surrounded surface of the coin, carefully 
removing all air bubbles. Now fill up the cavity with a thick 
paste of plaster of Paris in water. Allow to dry, and carefully re- 
move the paper strip and coin. 

H. Taste a little alum. Heat some on charcoal. Observe all the 
changes closely. Intumescence. 

III. Dip one end of a strip of cotton cloth into a strong solution 
of potash alum, then into a decoction of maddei (a dye-stuff). 
Remove and wash. Repeat the experiment, substituting iron 
alum. Decoctions are made by boiling the substance in water. 



LESSON XXXIV. 



SILICATES:— NATURAL AND ARTIFICIAL 

239. Natural Silicates. — There is an element 
called silicon, very similar to carbon. The element 
does not occur free, however, but combined with oxygen 
it is very abundant, composing about one-half of the 
earth's crust. Quartz and the whitest varieties of sand 
are almost pure silica, silicon dioxide. The free acids, 



136 SCHOOL CHEMISTRY. 

and there are several, can be prepared in the labora- 
tory, but they never occur in nature. Their salts, 
brought about by the union of silica with the different 
metallic oxides, constitute our rocks and soil. Of 
these natural silicates we might note feldspar, a double 
silicate of aluminum and potassium, and mica, some- 
times improperly called isinglass, a complex silicate of 
the same metals and sometimes with iron. 

240. Artificial- Silicates. — Besides the great num- 
ber of natural silicates there are some artificial ones of 
the greatest importance and use in the arts and our 
every-day life. The silicates are as a rule insoluble in 
water, but there are two, sodium and potassium sili- 
cates, which, because they are soluble, go by the name 
of " water glass." This is much used by soap makers 
and calico printers. It is also used to make artificial 
stone, for when mixed with calcium hydroxide or car- 
bonate it forms calcium silicate, which is not only 
insoluble in water, but acts as a cement for sand and 
rocks. 

241. Mortar. Cement. Ordinary mortar is a 
mixture of slaked lime with sand. When most of the 
water of the mixture dries out the crystalline calcium 
hydroxide is formed. This acts as a binding material 
to hold the sand in place. Carbon dioxide is slowly 
absorbed from the air, and the hydroxide gradually 
changes after long exposure to the firmer calcium car- 
bonate. Ordinary mortar can be washed away or 
disintegrated by water. We frequently need a similar 



SILICATES- — NATURAL AND ARTIFICIAL. 137 

binding material for bridge piers, wharves, etc., that are 
exposed to the continuous action of water. Hydraulic 
cement is prepared by igniting a mixture of limestone, 
clay, and powdered quartz. When stirred up with 
water this mixture hardens, which depends upon the 
formation of the insoluble calcium silicates and alumi- 
nates. 

242. Glass. — The most important use of sodium 
and potassium silicates is in the making of glass. The 
various kinds of glass of commerce are mixtur.es of 
highly siliceous sodium and potassium silicates with 
the silicates of calcium or lead. Most of the natural 
silicates are crystalline, but the transparent value of 
glass depends upon its amorphous condition. The sil- 
icates of the alkali metals, when not too siliceous, are 
amorphous, but soluble in water. The silicates of the 
other metals are insoluble, but tend to crystallize when 
cooled from the molten state. Window glass must hot 
only be transparent, but withstand the solvent action 
of the rains ; therefore, the silicates of sodium and cal- 
cium are mixed in such judicious proportions as to 
retain both the non-crystalline and insoluble proper- 
ties. Some cheap forms of window glass scale, and 
become dull as the result of the action of air and water. 

243. Varieties of Glass. — Bohemian, or hard glass, 
so much used by chemists, consists of the silicates of 
calcium and potassium. It is only slightly acted upon 
by acids and alkalies, and melts only at a high tem- 
perature. Flint glass contains lead, causing it to 



138 SCHOOL CHEMISTRY. 

melt more easily. On account of its valuable optical 
properties it is used for making lenses for telescopes 
and other optical instruments. As these lenses must 
be cast, cut, and polished, a soft glass must be used. 
Ordinary bottle glass is composed of the silicates of 
calcium, iron, aluminum and potassium. As many 
metallic silicates are colored, the oxides of these metals 
are mixed with the silicates to produce the various 
colored glasses. For instance, green bottle glass is due 
to the presence of ferrous silicate ; cobalt gives a blue, 
manganese a violet, uranium a green-yellow, copper- 
green, or red and gold ruby red. 

244. Borates. — Borax (sodium ' tetraborate) acts 
very like the silicates. The glasses formed are much 
more easily melted. 

EXPERIMENTS. 

I. Take soine plastering or mortar from an old building, and add 
HC1 to it. Pass the gas through lime water. 

II. Pour 30 cc. water glass into a vessel ; pour on it half as much 
dilute sulphuric acid, having care that the two do not mix. Pour 
immediately into another vessel ; silica should separate in long 
tubes resembling stalactites. 

III. Powder finely some window glass in a mortar ; place some 
of the powder upon moist red litmus paper, and allow it to remain 
there for several minutes. 

IV. Try to dissolve some sand in water. Mix some of it in a 
powdered state with four times as much sodium carbonate and 
potassium nitrate, and heat strongly with the blowpipe for ten 
minutes on a piece of platinum or charcoal. When cold, test so- 
lubility in water. 



THE SOIL. 139 

LESSON XXXV. 

THE SOIL. 

245. The Soil. — What we are so accustomed to see 
is not likely to attract our close attention. All admire 
a beautiful green field of grain undulating with the 
breezes. A hillside covered with golden stacks of ripe 
oats is a beautiful sight. But how little thought do 
we give the ground, that repulsive dirt which fostered 
and nourished Nature's lovely growth ! It is well to 
shun filth, but the soil should claim not only our 
attention and respect, but affection, in fact. All ani- 
mal and plant life are directly or indirectly dependent 
upon the soil's generous allowances. 

246. Source of Soil. — In our other nature studies 
we learn more about the soil. For our purpose, how- 
ever, we may say that the soil is decomposed rock, the 
disintegration being brought about by nature's agents — 
the weather, oxygen, erosion, plants and animals. All 
of us have seen stones worn away and crumbled by 
long exposure to the action of the atmosphere, rain 
and changes in temperature. In many cases, this 
powdered rock is borne away by the action of water, 
either as rain, streams or springs, and deposited anew 
in some other place. Such soil as is found in the Mis- 
sissippi bottom lands and the Yadkin Valley, is called 
alluvial. It has been estimated that the Mississippi 
river carries, dissolved, one hundred and fifty million 



140 SCHOOL CHEMISTRY. 

tons of matter, and three hundred and fifty million 
tons of suspended matter annually, into the Gulf. 

247. General Similarity in Composition of 
Soils. — Since the soil is decomposed rock, it contains 
the constituents of the original rocks. As the kinds of 
rocks, dependent upon their mineral constituents, vary 
in different places, the soils should be unlike. Soils 
do vary in character, of course, but most of the rock 
constituents are a little soluble in water. The con- 
tinuous action of the water would thus carry portions 
from one locality through and across the surface of the 
soil and over great distances to another resting place. 
The winds and surface water, with burrowing worms, 
and plants, too, tend to alter, change, transport and 
mix the soil, so wherever it is formed there is a general 
similarity in composition. 

248. Elements Present in Soil. — Of the many 
chemical elements found in the soil, the following are 
the most abundant and are of the greatest importance 
from an agricultural standpoint : Non-metals — oxygen, 
silicon, carbon, sulphur, chlorine, phosphorus, fluorine, 
nitrogen and boron ; metals — hydrogen, aluminum, 
calcium, magnesium, potassium, sodium, iron and 
manganese. Silicon and oxygen are the most abund- 
ant elements in the soil, the former always being com- 
bined with the latter. This oxide, silica, which we 
know as quartz, is a very hard insoluble substance, 
hence is always most abundant in soil, as it wears so 
slightly and is not easily washed away. This sand is 
present even in the very clayey soils. 



THE SOIL. 141 

249. Essential Elements. — The clay of soils is 
dependent upon the third most abundant element, 
aluminum. This metal is a prominent constituent of 
feldspars and the different micas, rocks which, on de- 
composing, produce clay. The other elements men- 
tioned are all quite necessary when the soil is called 
upon to fulfil its greatest duty, but they are present in 
much smaller amounts than the other three. In rela- 
tion to the soil, carbon is present in humus (organic 
matter), carbonates and gaseous carbon dioxide. Sul- 
phur is present in iron sulphide (fool's gold) and sul- 
phates. Hydrogen, not free, but combined with oxy- 
gen in water, is most important. Phosphorus as phos- 
phates, is a constituent of the oldest rocks, hence, 
through the process of decay and rock building, it has 
found its way into the soils of all geologic ages. The 
phosphates are absolutely essential, and are always 
present, as are also calcium, magnesium, iron and 
manganese. Potassium is one of the indispensably 
necessary plant foods, and it is almost universally dis- 
tributed in the soils, but its salts are very soluble in 
water. Sodium is very similar, chemically, to potas- 
sium, and is always present, but somehow it cannot 
in any way take the place of potassium in the life of 
land plants. 

250. Nitrification. — Nitrogen, though so abundant 
in the atmosphere, is least abundant as a rock ingre- 
dient in the earth's crust. It is present in the frag- 
ments of decaying tissues of plants and animals. 
Plants secure much of their necessary nitrogen by the 



142 SCHOOL CHEMISTRY. 

action of the rains which scrub the air, removing the 
ammonium compounds with nitric acid. 

251. Bacterial Inhabitants. — Besides these chem- 
ical elements existing in all kinds of combinations, 
there are infinite numbers of lower microscopic forms 
of life which accomplish wonders, especially in the 
process of nitrification — that is, the rendering of nitro- 
gen available to the plant. It is through this agency 
that the organic matter is caused to decay, thereby 
changing the nitrogen into nitric acid, or its salts, as 
potassium nitrate, which becomes at once useful as 
plant food. Each farmer has an unpaid corps of faith- 
ful laborers. 

252. Source of Heat. — The soil permits the sun- 
shine to accomplish the great work of nature. The 
manner in which soil is tilled, permitting loose disin- 
tegration for draining away the excess of water and 
maintaining the proper amount during drought, and 
the way in which it is otherwise strengthened, have a 
great deal to do with the amount of work the sun's 
heat is able to do. 



LESSON XXXVI. 

SYNTHETIC LIFE. 

All of us know that 

"Large streams from little fountains flow, 
Tall oaks from little acorns grow." 

But how does it happen ? 



SYNTHETIC LIFE. 143 

253. Plant Life. — The acorn, the fruit of the oak 
tree, contains the seed, which under proper conditions 
should give rise to another oak. From your botany 
lessons you likely learned the structure of the acorn. 
Buried under the sod, through the influence of mois- 
ture and the sun's heat, the tiny plantlet sends up its 
plumule and downward its root. Nourished by the 
rich food encased in the shell, this product of vital 
force, which man can neither give nor create, heaves 
aside the crust of the earth, and its two tender leaves 
greet the sunshine. Immediately this small but per- 
fect object exercises acute judgment. Its little root 
noses around for some soluble food, as an infant takes its 
milk. The leaves gather strength and life from the 
sun and air, and the full grown tree in turn is evolved 
from one tiny cell. All life is such ; all life begins in 
just this way. No one can explain it. It is a point at 
which man with all his learning must stop and ac- 
knowledge the existence of some Higher Being, who 
can place life within a grain of wheat from which may 
rise an hundred more. 

254. Osmosis. — Of the seventy known elements 
about sixteen are invariably found in plants of differ- 
ent kinds. These elements are not found free in any 
instance, but in almost innumerable combinations. 
The plant existing half in the air and half in the soil, 
has two channels through which it may obtain its food. 
The roots and roothairs are covered with a porous mem- 
brane, through which all material entering the plant 
from the soil must pass. If we separate two liquids 



144 SCHOOL CHEMISTRY. 

by a porous membrane, each tends to pass through the 
membrane into the other. The lighter one moves much 
more rapidly. This diffusion of liquids through mem- 
branes is called osmosis, the principle upon which 
the acquisition of all liquid plant food from the soil 
depends. The pressure upward in plants resulting 
from this osmotic action is very strong at times. 

255. Liquid Vehicle. — Water, as we have seen, 
holds many of the salts of the soil in solution. The 
water carrying these salts of potassium, calcium, mag- 
nesium, sodium, iron, etc., usually as phosphates, ni- 
trates, chlorides or sulphates, is sucked through the 
root membrane. Once in this wonderful little cellu- 
lar workshop, the plant forms and fashions each to be 
most suitable for its use. 

256. Tobacco. — Some plants have peculiar appe- 
tites and make a special demand upon the soil for 
their gratification. Tobacco is especially greedy about 
potassium. About eight per cent, of the ashes on the 
end of a cigar is made up of that element. In fact, its 
use is not only a wasteful, expensive yet gratifying 
luxury, but a plant which produces very exhausting 
effects upon land. For example, fourteen tons of 
wheat, fifteen tons of corn, or twelve tons of oats re- 
move no more of the principles of fertility than does 
one ton of tobacco. 

257. Abundance of Plant Food in Soil. — Each 
plant requires more of a certain kind of food than 



SYNTHETIC LIFE. 145 

others. Each fertile soil by calculation contains, when 
new ground — that is, virgin soil — enough plant food 
to supply alternating crops of corn, oats, and clover for 
several hundred years, but with successively decreas- 
ing yields. If any one crop be grown continuously 
upon the same spot of ground, necessarily that form of 
inorganic food most required will gradually become 
exhausted in part, if not altogether. This exhaustion 
must be prevented by artificially replacing that which 
has been removed. Now phosphoric acid must always 
be present, also calcium and magnesium are necessary, 
as they are found in the seeds of the plants grown. 
As strange as it may seem, the refractory metal iron 
is necessary for the plant's growth. Hydrogen enters 
the plant combined with oxygen as water. Not a 
blade of grass nor a stalk of corn can grow without the 
gaseous element nitrogen. Although the plant is sur- 
rounded by millions of tons of it, it tastes it not as 
such. 

258. Necessity for Fertilizers. — The plant thus 
extracts rich food from the earth. Dying in place and. 
decaying where it knew its birth, it returns to the soil 
all that was loaned for its temporary use. Thus prim- 
eval forests always present a most luxuriant growth. 
If these plants be removed with their borrowed riches,, 
a generous soil lends it aid as long as its impoverished 
resources permit, but in time they become exhausted 
and "poor land" results. Man, for it is the result of 
his work, must make good the loss, if gain is still to be 
had. This is the cause of our having to fertilize 



146 SCHOOL CHEMISTRY. 

the fields. Those substances which can least afford 
being removed, but are as a rule carried away, are 
phosphoric acid, potassium, and nitrogen compounds. 
The amounts removed depend upon the crop. For in- 
stance, an acre of wheat yielding twenty-five bushels 
requires in straw and grain twenty-two kilograms of 
ammonia. Results of careful experiments show that 
under the most favorable circumstances only five kilo- 
grams of ammonia would be carried to the soil by 
rain. If all that were assimilated, seventeen kilos 
would still have to be added to meet the wants of this 
one wheat field. In actual practice this is not quite 
so, for as we learned there is another source from which 
much nitrogen is derived — namely, bacterial agents. . 

259. Kinds of Fertilizers. — Fertilizers are made 
up in accord with the results of these experiments, the 
amounts of these three constituents varying with the 
kind of crop to be fertilized. The phosphoric acid is 
obtained as bones or phosphate rock, treated with sul- 
phuric acid, and utilized as " acid phosphate." Potas- 
sium is used in the form of any of its salts, or in cotton- 
seed meal. Nitrogen is added as ammonium com- 
pounds or nitrates or nitrogenous organic material, 
as fish scale or scrap. Farmers sometimes think that 
the more the fertilizer resembles the black rich dirt of 
the woods the more valuable it is. Although that has 
nothing whatever to do with the value of the fertilizer, 
manufacturers frequently darken their fertilizers with 
soot or powdered charcoal. 



SYNTHETIC LIFE. 147 

260. Fixation of Carbon. — Now, there is one ele- 
ment which constitutes by far the greater portion of 
the plant, if we except the constituents of water, and 
which is absolutely necessary for its growth, and yet 
the farmer does not have to pay for it. That brings 
us to the other road by which plants acquire food — the 
leaves. You who have studied botany know that each 
leaf has many mouths, called stomata, through which 
we might say they breathe. Just underneath the thin 
outer skin of the leaf in the tiny cells there exists 
a complicated chemical compound, which contains 
carbon, hydrogen, oxygen, and iron, called chlorophyll. 
This is the green coloring matter of the leaves. 
Through the tiny leaf mouths the sluggish gas, carbon 
dioxide, passes ; combining with water, which has 
come up from the roots, this gas passes into the little 
cells, where, under the influence of the sun's rays and 
the guidance of the chlorophyll, new fiber is generated 
and oxygen gas is liberated. The oxygen is breathed 
out from the pores, and diffuses into the air. The 
fresh air, hovering over a dense forest, thus contains a 
trifle more oxygen than does the ordinary air. In fact, 
this is the source from which we obtain all the oxygen 
we breathe. 

EXPERIMENTS. 

I. Place in a dish spring water, to which has been added one- 
fourth as much carbonated water, obtained from any soda foun- 
tain. Place several sprigs of mint or other succulent plant in an 
empty quinine bottle, and fill it with the water. Invert the bottle 
in the dish, being careful that no air gets in. (Fig. 13.) Expose 
to direct sunlight for two hours. Carefully remove the plants, 



148 SCHOOL CHEMISTRY. 

detaching the bubbles from each leaf, without admitting any ah\ 
Place a card under the mouth of the bottle and invert. Test the 
gas with a lighted taper. 




Fig. 13. 



LESSON XXXVII. 
THE CYCLE OF LIFE. 



From our last lesson we learned that plants are al- 
ways gathering together simple materials, and con- 
structing complicated highly organized products. Now 
what part does the animal play in Nature's grand sys- 
tem of economy ? 

261. Animal Growth. — By the goodness of the 
Divine Being we are given life. Neither chemistry 
nor any branch of science can or dares to explain that. 
Our existence is the result solely of God's wonderful 
beneficence. Science seeks to explain as far as possible 
what takes place under the influence of that God-given 
power, life. Suppose we take any one of us young 
people as an example. We have life ; our tiny bodies 
were given us to begin with, and we by our efforts 



THE CYCLE OF LIFE. 149 

have grown. To cause the body to increase in size we 
must furnish the material for its upbuilding in differ- 
ent forms of food. We have learned something of the 
chemical elements which enter into plants. Directly 
or indirectly we live upon plants, therefore the sub- 
stances which build up our structure serve us in the 
same way. The architect, life, builds not only accord- 
ing to the material furnished, but fashions each as it 
seems best. 

262. Cooking. — By means of the digestive organs 
and various liquid systems learned of from your phys- 
iology, the food material is made available, and pro- 
perly distributed throughout the body. It may be well 
to remark here that while some kinds of food stuff 
would require less work on the part of the animal body 
to digest if it were not cooked, that the cooking of food 
makes it more palatable, and promotes a greater desire 
for its consumption, just as proper seasoning of food 
causes the more ready flow of the digestive fluids, 
hence greater ease in digestion. For example, the al- 
bumen of an egg, the white, is thoroughly digestible 
raw, but if it be cooked, hard boiled, it becomes less 
digestible and requires great expenditure of energy to 
get it once more into an available state. 

263. Similarity in Composition. — Arising from 
the glowing embers of a fire is the colorless gas, carbon 
dioxide, the result of the oxidation of the carbon in the 
coal or wood. Carried out over the earth in the air 
this gas is sucked in by the bright-green leaves, and 



150 SCHOOL CHEMISTRY. 

serves as the foundation principle of the prettiest rose 
or sweetest sugar or rankest smelling onion. This 
plant material is then utilized by man as food at once, 
or he eats the ox that has devoured it. Thus we see 
that carbon may in time give beauty to the cheek of 
our prettiest girl friend, the result of chemical action 
and life force. We are all composed alike. Carbon 
has been selected merely as an illustration of a princi- 
ple which is true of all the elements entering into 
the composition of the animal body. 

264. Air a Necessity. — Now men have been 
known to live quite awhile without food. Dr. Tanner 
fasted forty days. Shipwrecked sailors on the ocean 
have been known to remain without food and water 
for six days, but no man has ever been heard of who 
lived for more than a few minutes without breathing. 
Although food is essential for our upbuilding, growth, 
even our mere continued existence, and while water is 
also necessary as a vehicle of food, and for keeping up 
the liquid state of the many animal fluids, yet the air 
is the most essential. Why ? 

265. Animal Heat. — The air, active oxygen diluted 
with inert nitrogen, is carried into the lungs where it 
comes into close contact with the blood by diffusion 
through a thin membranous wall. A constituent of 
the blood, haemoglobin, a chemical compound, has the 
power of combining with oxygen and bearing it away 
from the lungs throughout the body. When this oxy- 
gen is thus carried into the capillary blood vessels, it 



THE CYCLE OF LIFE. 151 

becomes exceedingly active and burns up certain por- 
tions of the animal body, mainly carbon compounds. 
We have seen that when chemical action takes place 
heat is produced. Not only is our temperature kept 
up to the normal by this, but carbon dioxide is liber- 
ated. It is dissolved in the blood and borne back to 
the lungs, and there turned loose in the air, where it is 
rapidly diffused. Pure air breathed into the lungs re- 
turns ladened with impurities, carbon dioxide being 
the greatest. 

266. Animal Life Analytic. — Thus we see that 
plants are forever withdrawing carbon dioxide from 
the air and building up food material ; animals are- 
using that food and throwing the carbon dioxide back 
upon the air. Plant life is therefore on the whole 
synthetic, upbuilding ; animal life is analytic or break- 
ing down. Yet with all these great changes the amount 
of carbon dioxide in the air remains almost constant, 
about four parts in ten thousand. This has been so* 
for years and is likely to continue. 

267. Debt to God. — When we stop to think, al- 
though seemingly a small matter, this is a most deli- 
cate balancing of our very existence. No such nice 
arrangement could be maintained except by an all 
powerful, and, as it is exactly suited for our best exist- 
ence in this world, an Allwise Providence. And chem- 
istry, to which some have attributed an opposition to 
religion, can do nothing but beg all to join in praise 
to God " from Whom all blessings flow." 



JLIFIPIEILTIDIIX 



Apparatus and Chemicals Kequired. 



10 common Blowpipes. 
Sheet platinum, 2 x 10 cm. 
10 Funnels, top 5 cm. diam. 

1 Thermometer, 0—360° C. 

3 lbs. soft glass Tubing, 4 mm. 

diam. 
Corks, 2 doz. each 1 and 2 cm. 

diam. 
Fourth quire Litmus paper, half 

red. 
100 Filter papers, 595 S. & S. 

11 cm. diam. 
5 doz. Test Tubes, 2 cm. x 15 

cm. 
10 porcelain Dishes, 5 cm. diam. 

2 small porcelain Mortars. 



12 round bottom Flasks, 100 cc. 
cap. 
1 book Dutch Leaf. 
Platinum Wire, 1 m. (small). 
Iron wire Gauze, 12 cm. x 1 m. 
12 Erlenmeyer Flasks, 250 cc. 
3 metres soft rubber Tubing, 

4 mm. diam. 
Common Bottles, 12, each 200, 

250 and 500 cc. cap. 
1 quire Absorbent Paper. 
10 Iron Tweezers (small). 
5 Clay Pipes. 
3 Graduates, 50 cc. 
10 pieces Mica, 2x6 cm. 



i kilo. 
3 kilos. 
2 kilos. 
2 kilos. 
150 grams. 
1^ kilos. 
120 grams. 
120 grams. 
60 grams. 

J kilo. 

i kilo. 

£ kilo. 
* kilo. 
30 grams. 
10 grams. 
30 grams. 
15 grams. 
£ kilo. 

120 grams. 



Acetic acid 

Hydrochloric acid... 

Nitric acid 

Sulphuric acid 

Tannic acid 

Ammonia 

Ammonium chloride 

Ammonium nitrate. 

Sodium (metallic)... 

Sodium silicate 
(water glass).... 

Sodium hyposul- 
phite 

Sodium hydroxide, 
crude 

Iron sulphide 

Iron alum 

Iodine 

Potassium iodide. ... 

Potassium (metallic) 

Potassium chlorate, 

Potassium nitrate, 
crude cryst 

The above, enough for ten pupils, may be procured for twenty- 
five dollars from Eimer & Amend, New York. One dollar per 
pupil should cover cost of material and breakage. 



Lead oxide (red lead) 

Lead nitrate 

Lead acetate (com.), 
Sulphur (brimstone) 
Antimony powder... 

Magnesium wire 

Magnesium powder, 

Silver nitrate 

Bone black 

Carbon dieulphide.. 
Copper sulphate, 

crude 

Bleaching powder... 

Aluminum wire 

Saccharine 

Mercuric chloride ... 
Strontium nitrate.... 

Barium nitrate 

Madder 

Phosphorus 

Manganese dioxide 

powder 



120 grams. 
120 grams. 
* kilo. 
120 gr. 
15 gr. 
30 gr. 
60 gr. 
30 gr. 
250 grams. 
500 grams. 

250 grams. 
500 grams. 
30 grams. 
1 gram. 
15 grams. 
250 grams. 
250 grams. 
30 grams. 
60 grams. 

500 grams. 



ustideik: 



Absolute Alcohol 79 

Absorption 15 

Acids 42, 56 

" Acetic 83 

" Cyanic 90 

" Hydrochloric 41 

" Hydrocyanic 90 

" Lactic 87 

" Muriatic 38, 42 

" Nitric 44 

" Organic 82 

" Tannic 92 

Acid oxides 56, 95 

Acid phosphate 135, 142 

Acid salt 72, 126, 131 

Adjective colors 133 

iErial ocean 26 

Air 26 

" A mixture 27 

" Thickness of 26 

Alchemists 18 

Alcohols 78 

Alkaloids 90 

Allotropism 23, 46 

Alloys 107 

Alluvial soils 139 

Aluminum 54, 98 

" Bronze 99 

Potassium sili- 
cate 136 

Sulphate 133 

Alums 133 

Amalgams 101 

Amber 93 

Ammonia 36 



Ammonium cyanate 90 

Phosphate 71 

Aluminum sul- 
phate 133 

Amorph ous 46 

Analysis.... 58 

Animal growth 148 

Heat 150 

World 73 

Anthracite 49 

Antimony 54 

Aqua fortis 44 

Aqua regia 105 

Argon 54 

Arsenic 54 

Atmosphere 26 

Atomicity 53 

Atomic theory 17, 18 

Atoms 17 

Auer-Welsbach 118 

Barium 1 54 

Bacteria 142 

Baking powders 133 

Balsam 93 

Base , 56 

" Metal in 

Basicity of acids 71 

Basic oxides 56, 95 

" salt 130 

Beer 80 

Bell metal 108 

Beverages 80 

Bismuth 54 

Bituminous coal 49 



154 



SCHOOL CHEMISTRY. 



Bleaching 39, 67 

Powder 40 

Blowing in 114 

Bluestone 132 

Body heat 29 

Bohemian glass 137 

Boiling point 14 

Bone-black 48 

Bone phosphate 71 

Borates 138 

Borax 138 

Boron 54 

Bottle glass 138 

Brandy 81 

Brass 108 

Brimstone 63 

Bromine 54 

Bronze 108 

Brown coal 49 

Batter 85 

Cadmium 54 

Caffeine 91 

Calcium 54 

Light 118 

" Hydrogen phos- 
phate 135 

Silicate 136 

Sulphate 131 

Cane sugar 86 

Cannel coal 49 

Carats 106 

Carbohydrates 86 

Carbon 46, 54 

Carbonates 126 

Carbonic acid 60, 127 

Carbon dioxide 29, 60 

" Disulphide 65 

" Monoxide 59 

Carboxyl 83 



Casting 109 

Cast Iron 113 

Castner Kellner process 129 

Caustics 96 

Caustic potash 96 

" soda 95 

Celluloid 88 

Cellulose 88 

Cement 136 

Cerium 54 

Cesium 54 

Cinnabar 101 

Chalybeate 15 

Charcoal 48 

Chemical affinity 20 

" Change 32 

" Equations 50, 53 

Solution 19 

Chili Saltpetre 124 

Chlorides 39, 119 

Chloride of lime 40 

Chlorine 38, 54 

Chloroform 78 

Chlorophyll 147 

Chrome alum 133 

Chromium 54 

Coal 48 

Cobalt 54 

Coffee 91 

Cohesion 13 

Coke 48 

Coldshort 112 

Collodion 88 

Columbium 54 

Combustible 31 

Combustion 31 

Compounds 118 

Compound radicals 57 

Conservation of matter 11 

Cooking 149 



INDEX. 



155 



Cooking soda 127 

Copper 54, 104 

Copperas 67, 133 

Copper sulphate 132 

Crystallization 123 

Cyanates 90 

Cyanogen 90 

Cycle of life 148 

Davy, Sir H 44, 75 

Dalton 18 

Death valleys 61 

Decrepitation 121 

Definite proportions, Law of, 23 

Dew 30 

Dextrin 80 

Dextrose 88 

Diamonds, Artificial 47 

Distillation 16 

Division of matter 10 

Double salt 73 

Ductility 106 

Dust, Air 29 

Dynamite 126 

Electric furnaces 98 

Electrolysis 95 

Electrolytes. 56 

Electro-negative 56 

" positive 56 

Elements 18, 50 

Epsom salts 131 

Erbium 54 

Essential oils 92 

Esters 84 

Ether, Class 82 

Ethyl ether 82 

" Alcohol 79 

Evaporation 14 

Explosions 75 

Explosives 88, 135 



Fats 84 

Feldspar 136 

Fermentation 79 

Ferrous sulphate 133 

Fertilizers 145 

Fire damp 78 

Fixation of carbon 147 

Flame 31 

'' Reactions 96 

Flash lights 97 

Flint glass 137 

Flowers of sulphur 63 

Fluorine 54 

Fluxing 112 

Flying machines 98 

Fool's gold 63 

Formulas 50 

Galena 63 

Gallium 54 

Galvanized iron 100 

Gems 117 

Germanium 54 

Glass 137 

Glauber's salts 131 

Glucinum 54 

Glycerine (glycerol) 84 

Gold 54, 105, 106 

Grape sugar 86 

Graphite, 47 

Gray cast iron 113 

Gums, Arabic 89 

" Tragacanth 89 

Gun cotton 88 

Gunpowder 124 

Gypsum 131 

Haemoglobin 150 

Hard Glass 137 

" Solder 110 



15G 



SCHOOL CHEMISTRY. 



Hard soap 96 

" Water 15 

Hartshorn 29 

Heat 33 

Helium 54 

Hematites Ill 

Honey 86 

Horn silver 122 

Hot short 112 

Hydraulic cement 137 

Hydrogen. 17 

Sulphide 64 

Hydroxyl 57 

Ignition 32 

Paint 34 

Incandescence • 32 

India rubber 93 

Indium 54 

Ink 92 

Iodine 54 

Iridium 51 

Iron. 54, 111 

Iron alum 133 

" Furnace 112 

(i Pyrites 63 

Jewels 47 

Jupiter amnion 36 

Lamp black 48 

Lanthanum 54 

Laudanum 91 

Laughing gas 44 

Lavoisier 22 

Lead 54. 102 

" Oxides 115 

" Tree 100 

Leblanc process 128 

Leat her 92 



Life 118 

Lime 115 

Lithia water 15 

Lithium 54 

Litmus 43 

Luminosity 76 

Luminous plane 32 

Lunar caustic... 126 

Magnesium 55, 97 

Powder 32 

Sulphate 131 

Magnetite Ill 

Malleability 106 

Manganese 55 

Manganese dioxide 22, 115 

Marsh gas 77 

Matter 10 

Melting point 14 

Mercury 55, 101 

Metallic oxides 115 

Metals 94 

" History of 94 

Metathesis 58 

Methane 77 

Mica 136 

Milk sugar 87 

Mineral paint.. 116 

Water 15 

World 73 

Mixture 15, 27 

Molecular vibrations 13 

Molecules 10 

Molybdenum 55 

Mordants 133 

Morphine 91 

Mortar , 136 

Mother of- vinegar 83 

Multiple proportions, Law of 59 
Muriatic acid 38 



INDEX. 



157 



Nascent state 39 

Neodymiuin 55 

Neutral salts 72 

Nickel 55 

Nicotine 91 

Nitrates 123 

Nitre 35 

" Plantations 123 

Nitrification 141 

Nitrogen 28, 35, 55 

Nitrogen oxides 44 

Nitro-glycerine 126 

Noble metals 105 

Nomenclature 50 

Nux vomica 91 

Occlusion 106 

Oil-paints 116 

Oil of turpentine' 93 

Oil of vitriol 67 

Oleate 84 

Oleomargarine 85 

Organic bases 90 

" Acids 82 

" Chemistry 73 

" Compounds 74 

" Hydroxides 78 

Salts 84 

Opium 91 

Ores 104 

Osmium 55 

Osmosis 143 

Oxidation 31 

Oxidizing flame 76 

Oxygen 21, 28, 55 

Ozone 23, 24 

Paints 116 

Palladium 55 

Palmitate 84 



Paper 89 

Paregoric 91 

Patina 109 

Peat 49 

Phosphates 71, 133 

Phosphate mines 134 

Phosphorus 55, 69 

red 71 

waxy 70 

" oxides 71 

Physical states 9 

Pitch 93 

Plant food 145 

" Life 143 

Plaster of Paris 132 

Plastic sulphur 61 

Platinum 55, 105, 106 

Plumbago 47 

Poor land 145 

Potassium 55, 95, 144 

Aluminum sul- 
phate 133 

Chlorate 22 

" Iodide paper 24 

Nitrate 123, 124 

Praseodymium 55 

Precipitation 60 

Priestley 22 

Printer's ink 39 

Prussic acid 90 

Quartz 135 

Quick lime 115 

Quicksilver 101 

Quick vinegar process 83 

Quinine 91 

Eeducing flame 76 

Eesins 93 

Khodium 55 



158 



SCHOOL CHEMISTRY. 



Rochelle's salts 127 

Roll sulphur.. 63 

Rosin 93 

Rubber 93 

Rubidium 55 

Rust 31 

Ruthenium 55 

Safety lamp 75 

Sal-ammoniac 36 

Samariu m 55 

Saponification 84 

Salt 119 

" gardens 120 

Salting cattle 121 

Saltpetre 35, 123 

" Chili 45 

Salts 57, 72 

Salt springs 120 

Scandium 55 

Seidlitz powders 127 

Selenium 55 

Sheet tin 102 

Silicates, Artificial 136 

Natural 135 

Silicic acids 135 

Silicon 55 

Silicon dioxide 135 

Silver 55, 105 

Silver chloride 122 

" nitrate 126 

Slag 112 

Slaked lime 116 

Soap, soft and hard 84 

Soda 128 

Sodium 55, 95 

aluminum sulphate.. 133 

" bi-carbonate 127 

" carbonate 128 

" chloride 39, 119 



Sodium hydroxide 96 

nitrate 123, 125 

" phosphate 71 

11 sulphate 131 

Soft soap 96 

" solder 110 

Soil 129 

" Bacterial agents in 146 

" Composition of. 140 

" Elements in 140 

Solder 110 

Solution, Simple and chem- 
ical 14, 19 

Solvay process 129 

Sorghum 89 

Spontaneous combustion.... 33 

Spurious gold 108 

Starch 87 

" paper 24 

" paste 88 

Stalactites 130 

Stalagmites 130 

Stearate 84 

Steel 113 

Strontium 55 

Strychnine 91 

Substitution compounds 78 

Sugar 86 

Sulphates 131. 

Sulphides 64 

Sulphur 55, 63 

Sulphuretted hydrogen 64 

Sulphur dioxide 66 

Sulphuric acid 67 

Sulphur water 15, 65 

Supporter of combustion.... 34 

Symbols 50 

Synthesis 58 

Synthetic life 143 



INDEX. 



159 



Tannic acid 92 

Tannin.... 92 

Tanning 92 

Tantalum 55 

Tea 91 

Tellurium 55 

Tempering 114 

Temporary hardness 130 

Terbium 55 

Thalium 55 

Theine 91 

Thorium 55 

Thorium oxide 118 

Tin. 55, 102 

Titanium 55 

Tobacco 114 

Tri-acid bases 133 

Tri calcic phosphate 134 

Tungsien 55 

Turpentine 93 

Type-metal 109 

Uranium 55 

Urea 90 

Valence 50, 51 

Vanadium 55 

Vegetable world 73 



Vibratory motion 13 

Vulcanized rubber 94 

Washing soda 128 

Water colors 116 

" gas.. 59 

" glass 136 

" Omnipresence of 11 

" Synthetic production 

of. 23 

Watery vapor 29 

" " in air 30 

Whiskey 81 

White cast iron 113 

White lead 116 

White paint 116 

Window glass 137 

Wines 81 

Wine vinegar 83 

Wohler 74 

Wood alcohol 78 

Wrought iron 114 

Zinc 55, 99 

" Oxide 117 

" White 117 

Zirconium 55 

Zirconium oxide 118 



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